From 253b5bed74391a157172fe3dd54a290d2ce70653 Mon Sep 17 00:00:00 2001
From: Elliott Sprehn <esprehn@chromium.org>
Date: Wed, 26 Nov 2014 13:54:14 -0500
Subject: [PATCH] Only allow one shadowRoot.

R=ojan@chromium.org

Review URL: https://codereview.chromium.org/759663003
---
 benchmarks/dom/creation.sky                   |  2 +-
 engine/bindings/core/v8/V8GCController.cpp    |  7 +--
 engine/core/css/resolver/StyleResolver.cpp    |  2 +-
 engine/core/dom/ContainerNode.cpp             |  4 +-
 engine/core/dom/Element.cpp                   | 10 ++--
 engine/core/dom/Element.h                     | 10 +++-
 engine/core/dom/Element.idl                   |  2 +-
 engine/core/dom/Node.cpp                      | 42 +++------------
 engine/core/dom/Node.h                        |  2 +-
 engine/core/dom/TreeScope.cpp                 | 19 ++-----
 engine/core/dom/TreeScope.h                   |  1 -
 engine/core/dom/TreeScopeAdopter.cpp          |  8 +--
 engine/core/dom/TreeScopeTest.cpp             | 14 ++---
 engine/core/dom/shadow/ComposedTreeWalker.cpp | 12 +----
 engine/core/dom/shadow/ComposedTreeWalker.h   |  2 -
 engine/core/dom/shadow/ElementShadow.cpp      | 53 +++++++++----------
 engine/core/dom/shadow/ElementShadow.h        | 29 ++--------
 engine/core/dom/shadow/InsertionPoint.h       |  2 -
 engine/core/dom/shadow/ShadowRoot.cpp         | 15 ++----
 engine/core/dom/shadow/ShadowRoot.h           | 17 +-----
 engine/core/dom/shadow/ShadowRoot.idl         |  1 -
 engine/core/editing/TextIterator.cpp          | 21 ++------
 engine/core/events/EventPath.cpp              |  8 +--
 engine/core/page/FocusController.cpp          |  2 +-
 engine/web/tests/data/touch-action-tests.js   |  4 +-
 framework/sky-element/sky-element.sky         |  2 +-
 tests/dom/appendChild.sky                     |  2 +-
 tests/dom/replaceChild.sky                    |  2 +-
 tests/mutation-observer/shadow-dom.sky        |  2 +-
 29 files changed, 92 insertions(+), 205 deletions(-)

diff --git a/benchmarks/dom/creation.sky b/benchmarks/dom/creation.sky
index 71c9de23730..0f05fe9df89 100644
--- a/benchmarks/dom/creation.sky
+++ b/benchmarks/dom/creation.sky
@@ -14,7 +14,7 @@ WidgetPrototype.createdCallback =  function() {
   this.wasAttached = false;
   this.wasDetached = false;
   this.attrsChanged = [];
-  this.createShadowRoot();
+  this.ensureShadowRoot();
 };
 
 WidgetPrototype.attachedCallback = function() {
diff --git a/engine/bindings/core/v8/V8GCController.cpp b/engine/bindings/core/v8/V8GCController.cpp
index 606d98d440a..2f5df8ea1c5 100644
--- a/engine/bindings/core/v8/V8GCController.cpp
+++ b/engine/bindings/core/v8/V8GCController.cpp
@@ -171,14 +171,9 @@ private:
                 node->clearV8CollectableDuringMinorGC();
                 partiallyDependentNodes->append(node);
             }
-            if (ShadowRoot* shadowRoot = node->youngestShadowRoot()) {
+            if (ShadowRoot* shadowRoot = node->shadowRoot()) {
                 if (!traverseTree(shadowRoot, partiallyDependentNodes))
                     return false;
-            } else if (node->isShadowRoot()) {
-                if (ShadowRoot* shadowRoot = toShadowRoot(node)->olderShadowRoot()) {
-                    if (!traverseTree(shadowRoot, partiallyDependentNodes))
-                        return false;
-                }
             }
             // <template> has a |content| property holding a DOM fragment which we must traverse,
             // just like we do for the shadow trees above.
diff --git a/engine/core/css/resolver/StyleResolver.cpp b/engine/core/css/resolver/StyleResolver.cpp
index 1142ecec8b6..5aa48a10214 100644
--- a/engine/core/css/resolver/StyleResolver.cpp
+++ b/engine/core/css/resolver/StyleResolver.cpp
@@ -682,7 +682,7 @@ void StyleResolver::collectScopedResolversForHostedShadowTrees(const Element* el
         return;
 
     // Adding scoped resolver for active shadow roots for shadow host styling.
-    for (ShadowRoot* shadowRoot = shadow->youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot()) {
+    if (ShadowRoot* shadowRoot = shadow->shadowRoot()) {
         if (shadowRoot->numberOfStyles() > 0) {
             if (ScopedStyleResolver* resolver = shadowRoot->scopedStyleResolver())
                 resolvers.append(resolver);
diff --git a/engine/core/dom/ContainerNode.cpp b/engine/core/dom/ContainerNode.cpp
index d8d50024773..bafec230a8d 100644
--- a/engine/core/dom/ContainerNode.cpp
+++ b/engine/core/dom/ContainerNode.cpp
@@ -617,7 +617,7 @@ void ContainerNode::notifyNodeInsertedInternal(Node& root)
         if (!inDocument() && !node->isContainerNode())
             continue;
         node->insertedInto(this);
-        for (ShadowRoot* shadowRoot = node->youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot())
+        if (ShadowRoot* shadowRoot = node->shadowRoot())
             notifyNodeInsertedInternal(*shadowRoot);
     }
 }
@@ -634,7 +634,7 @@ void ContainerNode::notifyNodeRemoved(Node& root)
         if (!node->inDocument() && !node->isContainerNode())
             continue;
         node->removedFrom(this);
-        for (ShadowRoot* shadowRoot = node->youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot())
+        if (ShadowRoot* shadowRoot = node->shadowRoot())
             notifyNodeRemoved(*shadowRoot);
     }
 }
diff --git a/engine/core/dom/Element.cpp b/engine/core/dom/Element.cpp
index b0b9340fb28..7cb85c47be1 100644
--- a/engine/core/dom/Element.cpp
+++ b/engine/core/dom/Element.cpp
@@ -967,7 +967,7 @@ void Element::recalcChildStyle(StyleRecalcChange change)
     ASSERT(!needsStyleRecalc());
 
     if (change > Inherit || childNeedsStyleRecalc()) {
-        for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot()) {
+        if (ShadowRoot* root = shadowRoot()) {
             if (root->shouldCallRecalcStyle(change))
                 root->recalcStyle(change);
         }
@@ -1049,8 +1049,12 @@ CustomElementDefinition* Element::customElementDefinition() const
     return 0;
 }
 
-PassRefPtr<ShadowRoot> Element::createShadowRoot(ExceptionState& exceptionState)
+// TODO(esprehn): Implement the sky spec where shadow roots are a custom
+// element registration feature.
+PassRefPtr<ShadowRoot> Element::ensureShadowRoot(ExceptionState& exceptionState)
 {
+    if (ShadowRoot* root = shadowRoot())
+        return root;
     return PassRefPtr<ShadowRoot>(ensureShadow().addShadowRoot(*this));
 }
 
@@ -1059,7 +1063,7 @@ ShadowRoot* Element::shadowRoot() const
     ElementShadow* elementShadow = shadow();
     if (!elementShadow)
         return 0;
-    return elementShadow->youngestShadowRoot();
+    return elementShadow->shadowRoot();
 }
 
 void Element::childrenChanged(const ChildrenChange& change)
diff --git a/engine/core/dom/Element.h b/engine/core/dom/Element.h
index 432a886b00d..4f5a234c1a1 100644
--- a/engine/core/dom/Element.h
+++ b/engine/core/dom/Element.h
@@ -209,9 +209,8 @@ public:
 
     ElementShadow* shadow() const;
     ElementShadow& ensureShadow();
-    PassRefPtr<ShadowRoot> createShadowRoot(ExceptionState&);
+    PassRefPtr<ShadowRoot> ensureShadowRoot(ExceptionState&);
     ShadowRoot* shadowRoot() const;
-    ShadowRoot* youngestShadowRoot() const;
 
     bool hasAuthorShadowRoot() const { return shadowRoot(); }
 
@@ -547,6 +546,13 @@ inline void Node::removedFrom(ContainerNode* insertionPoint)
         clearFlag(IsInShadowTreeFlag);
 }
 
+inline ShadowRoot* Node::shadowRoot() const
+{
+    if (!isElementNode())
+        return 0;
+    return toElement(this)->shadowRoot();
+}
+
 inline void Element::invalidateStyleAttribute()
 {
     ASSERT(elementData());
diff --git a/engine/core/dom/Element.idl b/engine/core/dom/Element.idl
index e1025a39ab8..943b3a8f177 100644
--- a/engine/core/dom/Element.idl
+++ b/engine/core/dom/Element.idl
@@ -64,7 +64,7 @@
 
     [PerWorldBindings] readonly attribute DOMTokenList classList;
 
-    [RaisesException, MeasureAs=ElementCreateShadowRoot] ShadowRoot createShadowRoot();
+    [RaisesException] ShadowRoot ensureShadowRoot();
     [PerWorldBindings] readonly attribute ShadowRoot shadowRoot;
     NodeList getDestinationInsertionPoints();
 
diff --git a/engine/core/dom/Node.cpp b/engine/core/dom/Node.cpp
index 7046078076c..aa0895c7e86 100644
--- a/engine/core/dom/Node.cpp
+++ b/engine/core/dom/Node.cpp
@@ -459,17 +459,6 @@ bool Node::hasNonEmptyBoundingBox() const
     return false;
 }
 
-#ifndef NDEBUG
-inline static ShadowRoot* oldestShadowRootFor(const Node* node)
-{
-    if (!node->isElementNode())
-        return 0;
-    if (ElementShadow* shadow = toElement(node)->shadow())
-        return shadow->oldestShadowRoot();
-    return 0;
-}
-#endif
-
 void Node::recalcDistribution()
 {
     if (isElementNode()) {
@@ -482,7 +471,7 @@ void Node::recalcDistribution()
             child->recalcDistribution();
     }
 
-    for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot()) {
+    if (ShadowRoot* root = shadowRoot()) {
         if (root->childNeedsDistributionRecalc())
             root->recalcDistribution();
     }
@@ -533,7 +522,7 @@ unsigned Node::styledSubtreeSize() const
     for (const Node* node = this; node; node = NodeTraversal::next(*node, this)) {
         if (node->isTextNode() || node->isElementNode())
             nodeCount++;
-        for (ShadowRoot* root = node->youngestShadowRoot(); root; root = root->olderShadowRoot())
+        if (ShadowRoot* root = node->shadowRoot())
             nodeCount += root->styledSubtreeSize();
     }
 
@@ -1094,10 +1083,6 @@ unsigned short Node::compareDocumentPosition(const Node* otherNode, ShadowTreesT
                 if (!child1->isShadowRoot())
                     return Node::DOCUMENT_POSITION_PRECEDING | connection;
 
-                for (ShadowRoot* child = toShadowRoot(child2)->olderShadowRoot(); child; child = child->olderShadowRoot())
-                    if (child == child1)
-                        return Node::DOCUMENT_POSITION_FOLLOWING | connection;
-
                 return Node::DOCUMENT_POSITION_PRECEDING | connection;
             }
 
@@ -1200,10 +1185,7 @@ void Node::showNodePathForThis() const
     for (unsigned index = chain.size(); index > 0; --index) {
         const Node* node = chain[index - 1];
         if (node->isShadowRoot()) {
-            int count = 0;
-            for (ShadowRoot* shadowRoot = toShadowRoot(node)->olderShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot())
-                ++count;
-            fprintf(stderr, "/#shadow-root[%d]", count);
+            fprintf(stderr, "/#shadow-root");
             continue;
         }
 
@@ -1253,11 +1235,8 @@ static void traverseTreeAndMark(const String& baseIndent, const Node* rootNode,
         fprintf(stderr, "%s", indent.toString().utf8().data());
         node->showNode();
         indent.append('\t');
-        if (node->isShadowRoot()) {
-            if (ShadowRoot* youngerShadowRoot = toShadowRoot(node)->youngerShadowRoot())
-                traverseTreeAndMark(indent.toString(), youngerShadowRoot, markedNode1, markedLabel1, markedNode2, markedLabel2);
-        } else if (ShadowRoot* oldestShadowRoot = oldestShadowRootFor(node))
-            traverseTreeAndMark(indent.toString(), oldestShadowRoot, markedNode1, markedLabel1, markedNode2, markedLabel2);
+        if (ShadowRoot* shadowRoot = node->shadowRoot())
+            traverseTreeAndMark(indent.toString(), shadowRoot, markedNode1, markedLabel1, markedNode2, markedLabel2);
     }
 }
 
@@ -1293,13 +1272,8 @@ static void showSubTreeAcrossFrame(const Node* node, const Node* markedNode, con
         fputs("*", stderr);
     fputs(indent.utf8().data(), stderr);
     node->showNode();
-    if (node->isShadowRoot()) {
-        if (ShadowRoot* youngerShadowRoot = toShadowRoot(node)->youngerShadowRoot())
-            showSubTreeAcrossFrame(youngerShadowRoot, markedNode, indent + "\t");
-    } else {
-        if (ShadowRoot* oldestShadowRoot = oldestShadowRootFor(node))
-            showSubTreeAcrossFrame(oldestShadowRoot, markedNode, indent + "\t");
-    }
+    if (ShadowRoot* shadowRoot = node->shadowRoot())
+        showSubTreeAcrossFrame(shadowRoot, markedNode, indent + "\t");
     for (Node* child = node->firstChild(); child; child = child->nextSibling())
         showSubTreeAcrossFrame(child, markedNode, indent + "\t");
 }
@@ -1398,7 +1372,7 @@ void Node::removeAllEventListenersRecursively()
 {
     for (Node* node = this; node; node = NodeTraversal::next(*node)) {
         node->removeAllEventListeners();
-        for (ShadowRoot* root = node->youngestShadowRoot(); root; root = root->olderShadowRoot())
+        if (ShadowRoot* root = node->shadowRoot())
             root->removeAllEventListenersRecursively();
     }
 }
diff --git a/engine/core/dom/Node.h b/engine/core/dom/Node.h
index e4c21931070..4b854f23e73 100644
--- a/engine/core/dom/Node.h
+++ b/engine/core/dom/Node.h
@@ -212,7 +212,7 @@ public:
     // If this node is in a shadow tree, returns its shadow host. Otherwise, returns 0.
     Element* shadowHost() const;
     ShadowRoot* containingShadowRoot() const;
-    ShadowRoot* youngestShadowRoot() const;
+    ShadowRoot* shadowRoot() const;
 
     // Returns 0, a child of ShadowRoot, or a legacy shadow root.
     Node* nonBoundaryShadowTreeRootNode();
diff --git a/engine/core/dom/TreeScope.cpp b/engine/core/dom/TreeScope.cpp
index 5276416d3a7..446fc244d49 100644
--- a/engine/core/dom/TreeScope.cpp
+++ b/engine/core/dom/TreeScope.cpp
@@ -92,18 +92,9 @@ TreeScope::~TreeScope()
 #endif
 }
 
-TreeScope* TreeScope::olderShadowRootOrParentTreeScope() const
-{
-    if (rootNode().isShadowRoot()) {
-        if (ShadowRoot* olderShadowRoot = toShadowRoot(rootNode()).olderShadowRoot())
-            return olderShadowRoot;
-    }
-    return parentTreeScope();
-}
-
 bool TreeScope::isInclusiveOlderSiblingShadowRootOrAncestorTreeScopeOf(const TreeScope& scope) const
 {
-    for (const TreeScope* current = &scope; current; current = current->olderShadowRootOrParentTreeScope()) {
+    for (const TreeScope* current = &scope; current; current = current->parentTreeScope()) {
         if (current == this)
             return true;
     }
@@ -303,10 +294,6 @@ unsigned short TreeScope::comparePosition(const TreeScope& otherScope) const
             if (shadowHost1 != shadowHost2)
                 return shadowHost1->compareDocumentPosition(shadowHost2, Node::TreatShadowTreesAsDisconnected);
 
-            for (const ShadowRoot* child = toShadowRoot(child2->rootNode()).olderShadowRoot(); child; child = child->olderShadowRoot())
-                if (child == child1)
-                    return Node::DOCUMENT_POSITION_FOLLOWING;
-
             return Node::DOCUMENT_POSITION_PRECEDING;
         }
     }
@@ -414,7 +401,7 @@ Element* TreeScope::getElementByAccessKey(const String& key) const
     for (Element* element = ElementTraversal::firstWithin(root); element; element = ElementTraversal::next(*element, &root)) {
         if (equalIgnoringCase(element->getAttribute(HTMLNames::accesskeyAttr), key))
             result = element;
-        for (ShadowRoot* shadowRoot = element->youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot()) {
+        if (ShadowRoot* shadowRoot = element->shadowRoot()) {
             if (Element* shadowResult = shadowRoot->getElementByAccessKey(key))
                 result = shadowResult;
         }
@@ -425,7 +412,7 @@ Element* TreeScope::getElementByAccessKey(const String& key) const
 void TreeScope::setNeedsStyleRecalcForViewportUnits()
 {
     for (Element* element = ElementTraversal::firstWithin(rootNode()); element; element = ElementTraversal::next(*element)) {
-        for (ShadowRoot* root = element->youngestShadowRoot(); root; root = root->olderShadowRoot())
+        if (ShadowRoot* root = element->shadowRoot())
             root->setNeedsStyleRecalcForViewportUnits();
         RenderStyle* style = element->renderStyle();
         if (style && style->hasViewportUnits())
diff --git a/engine/core/dom/TreeScope.h b/engine/core/dom/TreeScope.h
index c3e05501d7f..3715293d339 100644
--- a/engine/core/dom/TreeScope.h
+++ b/engine/core/dom/TreeScope.h
@@ -48,7 +48,6 @@ class TreeScope {
 public:
     TreeScope* parentTreeScope() const { return m_parentTreeScope; }
 
-    TreeScope* olderShadowRootOrParentTreeScope() const;
     bool isInclusiveOlderSiblingShadowRootOrAncestorTreeScopeOf(const TreeScope&) const;
 
     Element* adjustedFocusedElement() const;
diff --git a/engine/core/dom/TreeScopeAdopter.cpp b/engine/core/dom/TreeScopeAdopter.cpp
index f378ee517a7..441eb59ce82 100644
--- a/engine/core/dom/TreeScopeAdopter.cpp
+++ b/engine/core/dom/TreeScopeAdopter.cpp
@@ -37,9 +37,7 @@ void TreeScopeAdopter::moveTreeToNewScope(Node& root) const
 {
     ASSERT(needsScopeChange());
 
-#if !ENABLE(OILPAN)
     oldScope().guardRef();
-#endif
 
     Document& oldDocument = oldScope().document();
     Document& newDocument = newScope().document();
@@ -54,16 +52,14 @@ void TreeScopeAdopter::moveTreeToNewScope(Node& root) const
         if (!node->isElementNode())
             continue;
 
-        for (ShadowRoot* shadow = node->youngestShadowRoot(); shadow; shadow = shadow->olderShadowRoot()) {
+        if (ShadowRoot* shadow = node->shadowRoot()) {
             shadow->setParentTreeScope(newScope());
             if (willMoveToNewDocument)
                 moveTreeToNewDocument(*shadow, oldDocument, newDocument);
         }
     }
 
-#if !ENABLE(OILPAN)
     oldScope().guardDeref();
-#endif
 }
 
 void TreeScopeAdopter::moveTreeToNewDocument(Node& root, Document& oldDocument, Document& newDocument) const
@@ -72,7 +68,7 @@ void TreeScopeAdopter::moveTreeToNewDocument(Node& root, Document& oldDocument,
     for (Node* node = &root; node; node = NodeTraversal::next(*node, &root)) {
         moveNodeToNewDocument(*node, oldDocument, newDocument);
 
-        for (ShadowRoot* shadow = node->youngestShadowRoot(); shadow; shadow = shadow->olderShadowRoot())
+        if (ShadowRoot* shadow = node->shadowRoot())
             moveTreeToNewDocument(*shadow, oldDocument, newDocument);
     }
 }
diff --git a/engine/core/dom/TreeScopeTest.cpp b/engine/core/dom/TreeScopeTest.cpp
index d943d16f49a..c8ca79cd827 100644
--- a/engine/core/dom/TreeScopeTest.cpp
+++ b/engine/core/dom/TreeScopeTest.cpp
@@ -21,7 +21,7 @@ TEST(TreeScopeTest, CommonAncestorOfSameTrees)
 
     RefPtr<Element> html = document->createElement("html", nullAtom, ASSERT_NO_EXCEPTION);
     document->appendChild(html, ASSERT_NO_EXCEPTION);
-    RefPtr<ShadowRoot> shadowRoot = html->createShadowRoot(ASSERT_NO_EXCEPTION);
+    RefPtr<ShadowRoot> shadowRoot = html->ensureShadowRoot(ASSERT_NO_EXCEPTION);
     EXPECT_EQ(shadowRoot.get(), shadowRoot->commonAncestorTreeScope(*shadowRoot));
 }
 
@@ -34,7 +34,7 @@ TEST(TreeScopeTest, CommonAncestorOfInclusiveTrees)
     RefPtr<Document> document = Document::create();
     RefPtr<Element> html = document->createElement("html", nullAtom, ASSERT_NO_EXCEPTION);
     document->appendChild(html, ASSERT_NO_EXCEPTION);
-    RefPtr<ShadowRoot> shadowRoot = html->createShadowRoot(ASSERT_NO_EXCEPTION);
+    RefPtr<ShadowRoot> shadowRoot = html->ensureShadowRoot(ASSERT_NO_EXCEPTION);
 
     EXPECT_EQ(document.get(), document->commonAncestorTreeScope(*shadowRoot));
     EXPECT_EQ(document.get(), shadowRoot->commonAncestorTreeScope(*document));
@@ -54,8 +54,8 @@ TEST(TreeScopeTest, CommonAncestorOfSiblingTrees)
     RefPtr<Element> body = document->createElement("body", nullAtom, ASSERT_NO_EXCEPTION);
     html->appendChild(body);
 
-    RefPtr<ShadowRoot> shadowRootA = head->createShadowRoot(ASSERT_NO_EXCEPTION);
-    RefPtr<ShadowRoot> shadowRootB = body->createShadowRoot(ASSERT_NO_EXCEPTION);
+    RefPtr<ShadowRoot> shadowRootA = head->ensureShadowRoot(ASSERT_NO_EXCEPTION);
+    RefPtr<ShadowRoot> shadowRootB = body->ensureShadowRoot(ASSERT_NO_EXCEPTION);
 
     EXPECT_EQ(document.get(), shadowRootA->commonAncestorTreeScope(*shadowRootB));
     EXPECT_EQ(document.get(), shadowRootB->commonAncestorTreeScope(*shadowRootA));
@@ -77,12 +77,12 @@ TEST(TreeScopeTest, CommonAncestorOfTreesAtDifferentDepths)
     RefPtr<Element> body = document->createElement("body", nullAtom, ASSERT_NO_EXCEPTION);
     html->appendChild(body);
 
-    RefPtr<ShadowRoot> shadowRootY = head->createShadowRoot(ASSERT_NO_EXCEPTION);
-    RefPtr<ShadowRoot> shadowRootB = body->createShadowRoot(ASSERT_NO_EXCEPTION);
+    RefPtr<ShadowRoot> shadowRootY = head->ensureShadowRoot(ASSERT_NO_EXCEPTION);
+    RefPtr<ShadowRoot> shadowRootB = body->ensureShadowRoot(ASSERT_NO_EXCEPTION);
 
     RefPtr<Element> divInY = document->createElement("div", nullAtom, ASSERT_NO_EXCEPTION);
     shadowRootY->appendChild(divInY);
-    RefPtr<ShadowRoot> shadowRootA = divInY->createShadowRoot(ASSERT_NO_EXCEPTION);
+    RefPtr<ShadowRoot> shadowRootA = divInY->ensureShadowRoot(ASSERT_NO_EXCEPTION);
 
     EXPECT_EQ(document.get(), shadowRootA->commonAncestorTreeScope(*shadowRootB));
     EXPECT_EQ(document.get(), shadowRootB->commonAncestorTreeScope(*shadowRootA));
diff --git a/engine/core/dom/shadow/ComposedTreeWalker.cpp b/engine/core/dom/shadow/ComposedTreeWalker.cpp
index b98e84a3c28..430bb865448 100644
--- a/engine/core/dom/shadow/ComposedTreeWalker.cpp
+++ b/engine/core/dom/shadow/ComposedTreeWalker.cpp
@@ -44,7 +44,7 @@ Node* ComposedTreeWalker::traverseChild(const Node* node, TraversalDirection dir
 {
     ASSERT(node);
     ElementShadow* shadow = shadowFor(node);
-    return shadow ? traverseLightChildren(shadow->youngestShadowRoot(), direction)
+    return shadow ? traverseLightChildren(shadow->shadowRoot(), direction)
             : traverseLightChildren(node, direction);
 }
 
@@ -105,14 +105,6 @@ Node* ComposedTreeWalker::traverseSiblingInCurrentTree(const Node* node, Travers
     ASSERT(node);
     if (Node* found = traverseSiblings(direction == TraversalDirectionForward ? node->nextSibling() : node->previousSibling(), direction))
         return found;
-    if (Node* next = traverseBackToYoungerShadowRoot(node, direction))
-        return next;
-    return 0;
-}
-
-Node* ComposedTreeWalker::traverseBackToYoungerShadowRoot(const Node* node, TraversalDirection direction)
-{
-    // FIXME(sky): Remove this.
     return 0;
 }
 
@@ -142,8 +134,6 @@ inline Node* ComposedTreeWalker::traverseParentOrHost(const Node* node) const
     if (!parent->isShadowRoot())
         return parent;
     ShadowRoot* shadowRoot = toShadowRoot(parent);
-    if (!shadowRoot->isYoungest())
-        return 0;
     return shadowRoot->host();
 }
 
diff --git a/engine/core/dom/shadow/ComposedTreeWalker.h b/engine/core/dom/shadow/ComposedTreeWalker.h
index 782dd6f7937..b5c68a39397 100644
--- a/engine/core/dom/shadow/ComposedTreeWalker.h
+++ b/engine/core/dom/shadow/ComposedTreeWalker.h
@@ -105,8 +105,6 @@ private:
     static Node* traverseSiblings(const Node*, TraversalDirection);
     static Node* traverseDistributedNodes(const Node*, const InsertionPoint*, TraversalDirection);
 
-    static Node* traverseBackToYoungerShadowRoot(const Node*, TraversalDirection);
-
     Node* traverseParentOrHost(const Node*) const;
 
     RawPtr<const Node> m_node;
diff --git a/engine/core/dom/shadow/ElementShadow.cpp b/engine/core/dom/shadow/ElementShadow.cpp
index 7a577491540..805ead131ef 100644
--- a/engine/core/dom/shadow/ElementShadow.cpp
+++ b/engine/core/dom/shadow/ElementShadow.cpp
@@ -129,16 +129,15 @@ PassOwnPtr<ElementShadow> ElementShadow::create()
 }
 
 ElementShadow::ElementShadow()
-    : m_needsDistributionRecalc(false)
+    : m_shadowRoot(0)
+    , m_needsDistributionRecalc(false)
     , m_needsSelectFeatureSet(false)
 {
 }
 
 ElementShadow::~ElementShadow()
 {
-#if !ENABLE(OILPAN)
-    removeDetachedShadowRoots();
-#endif
+    removeDetachedShadowRoot();
 }
 
 ShadowRoot& ElementShadow::addShadowRoot(Element& shadowHost)
@@ -146,13 +145,13 @@ ShadowRoot& ElementShadow::addShadowRoot(Element& shadowHost)
     EventDispatchForbiddenScope assertNoEventDispatch;
     ScriptForbiddenScope forbidScript;
 
-    for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot())
-        root->lazyReattachIfAttached();
+    ASSERT(!m_shadowRoot);
 
     RefPtr<ShadowRoot> shadowRoot = ShadowRoot::create(shadowHost.document());
     shadowRoot->setParentOrShadowHostNode(&shadowHost);
     shadowRoot->setParentTreeScope(shadowHost.treeScope());
-    m_shadowRoots.push(shadowRoot.get());
+    m_shadowRoot = shadowRoot.get();
+
     setNeedsDistributionRecalc();
 
     shadowRoot->insertedInto(&shadowHost);
@@ -160,42 +159,40 @@ ShadowRoot& ElementShadow::addShadowRoot(Element& shadowHost)
     return *shadowRoot;
 }
 
-#if !ENABLE(OILPAN)
-void ElementShadow::removeDetachedShadowRoots()
+void ElementShadow::removeDetachedShadowRoot()
 {
     // Dont protect this ref count.
     Element* shadowHost = host();
     ASSERT(shadowHost);
 
-    while (RefPtr<ShadowRoot> oldRoot = m_shadowRoots.head()) {
+    if (RefPtr<ShadowRoot> oldRoot = m_shadowRoot) {
         shadowHost->document().removeFocusedElementOfSubtree(oldRoot.get());
-        m_shadowRoots.removeHead();
+        m_shadowRoot = 0;
         oldRoot->setParentOrShadowHostNode(0);
         oldRoot->setParentTreeScope(shadowHost->document());
-        oldRoot->setPrev(0);
-        oldRoot->setNext(0);
     }
 }
-#endif
 
 void ElementShadow::attach(const Node::AttachContext& context)
 {
+    if (!m_shadowRoot)
+        return;
+
+    ASSERT(m_shadowRoot->needsAttach());
+
     Node::AttachContext childrenContext(context);
     childrenContext.resolvedStyle = 0;
-
-    for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot()) {
-        if (root->needsAttach())
-            root->attach(childrenContext);
-    }
+    m_shadowRoot->attach(childrenContext);
 }
 
 void ElementShadow::detach(const Node::AttachContext& context)
 {
+    if (!m_shadowRoot)
+        return;
+
     Node::AttachContext childrenContext(context);
     childrenContext.resolvedStyle = 0;
-
-    for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot())
-        root->detach(childrenContext);
+    m_shadowRoot->detach(childrenContext);
 }
 
 void ElementShadow::setNeedsDistributionRecalc()
@@ -209,9 +206,9 @@ void ElementShadow::setNeedsDistributionRecalc()
 
 bool ElementShadow::hasSameStyles(const ElementShadow* other) const
 {
-    ShadowRoot* root = youngestShadowRoot();
-    ShadowRoot* otherRoot = other->youngestShadowRoot();
-    while (root || otherRoot) {
+    ShadowRoot* root = m_shadowRoot;
+    ShadowRoot* otherRoot = other->shadowRoot();
+    if (root || otherRoot) {
         if (!root || !otherRoot)
             return false;
 
@@ -225,8 +222,6 @@ bool ElementShadow::hasSameStyles(const ElementShadow* other) const
             if (toCSSStyleSheet(list->item(i))->contents() != toCSSStyleSheet(otherList->item(i))->contents())
                 return false;
         }
-        root = root->olderShadowRoot();
-        otherRoot = otherRoot->olderShadowRoot();
     }
 
     return true;
@@ -251,7 +246,7 @@ void ElementShadow::distribute()
     host()->setNeedsStyleRecalc(SubtreeStyleChange);
     DistributionPool pool(*host());
 
-    for (ShadowRoot* root = youngestShadowRoot(); root; root = root->olderShadowRoot()) {
+    if (ShadowRoot* root = shadowRoot()) {
         const Vector<RefPtr<InsertionPoint> >& insertionPoints = root->descendantInsertionPoints();
         for (size_t i = 0; i < insertionPoints.size(); ++i) {
             InsertionPoint* point = insertionPoints[i].get();
@@ -276,7 +271,7 @@ const SelectRuleFeatureSet& ElementShadow::ensureSelectFeatureSet()
         return m_selectFeatures;
 
     m_selectFeatures.clear();
-    for (ShadowRoot* root = oldestShadowRoot(); root; root = root->youngerShadowRoot())
+    if (ShadowRoot* root = shadowRoot())
         collectSelectFeatureSetFrom(*root);
     m_needsSelectFeatureSet = false;
     return m_selectFeatures;
diff --git a/engine/core/dom/shadow/ElementShadow.h b/engine/core/dom/shadow/ElementShadow.h
index e097817bd7f..0f8f846f5f0 100644
--- a/engine/core/dom/shadow/ElementShadow.h
+++ b/engine/core/dom/shadow/ElementShadow.h
@@ -31,7 +31,6 @@
 #include "sky/engine/core/dom/shadow/SelectRuleFeatureSet.h"
 #include "sky/engine/core/dom/shadow/ShadowRoot.h"
 #include "sky/engine/platform/heap/Handle.h"
-#include "sky/engine/wtf/DoublyLinkedList.h"
 #include "sky/engine/wtf/HashMap.h"
 #include "sky/engine/wtf/Noncopyable.h"
 #include "sky/engine/wtf/PassOwnPtr.h"
@@ -46,8 +45,7 @@ public:
     ~ElementShadow();
 
     Element* host() const;
-    ShadowRoot* youngestShadowRoot() const { return m_shadowRoots.head(); }
-    ShadowRoot* oldestShadowRoot() const { return m_shadowRoots.tail(); }
+    ShadowRoot* shadowRoot() const { return m_shadowRoot; }
     ElementShadow* containingShadow() const;
 
     ShadowRoot& addShadowRoot(Element& shadowHost);
@@ -71,9 +69,7 @@ public:
 private:
     ElementShadow();
 
-#if !ENABLE(OILPAN)
-    void removeDetachedShadowRoots();
-#endif
+    void removeDetachedShadowRoot();
 
     void distribute();
     void clearDistribution();
@@ -88,30 +84,15 @@ private:
     NodeToDestinationInsertionPoints m_nodeToInsertionPoints;
 
     SelectRuleFeatureSet m_selectFeatures;
-    // FIXME: Oilpan: add a heap-based version of DoublyLinkedList<>.
-    DoublyLinkedList<ShadowRoot> m_shadowRoots;
+    ShadowRoot* m_shadowRoot;
     bool m_needsDistributionRecalc;
     bool m_needsSelectFeatureSet;
 };
 
 inline Element* ElementShadow::host() const
 {
-    ASSERT(!m_shadowRoots.isEmpty());
-    return youngestShadowRoot()->host();
-}
-
-inline ShadowRoot* Node::youngestShadowRoot() const
-{
-    if (!isElementNode())
-        return 0;
-    return toElement(this)->youngestShadowRoot();
-}
-
-inline ShadowRoot* Element::youngestShadowRoot() const
-{
-    if (ElementShadow* shadow = this->shadow())
-        return shadow->youngestShadowRoot();
-    return 0;
+    ASSERT(m_shadowRoot);
+    return m_shadowRoot->host();
 }
 
 inline ElementShadow* ElementShadow::containingShadow() const
diff --git a/engine/core/dom/shadow/InsertionPoint.h b/engine/core/dom/shadow/InsertionPoint.h
index 005c583ee43..82ade6bb884 100644
--- a/engine/core/dom/shadow/InsertionPoint.h
+++ b/engine/core/dom/shadow/InsertionPoint.h
@@ -95,8 +95,6 @@ inline ElementShadow* shadowWhereNodeCanBeDistributed(const Node& node)
     Node* parent = node.parentNode();
     if (!parent)
         return 0;
-    if (parent->isShadowRoot() && !toShadowRoot(parent)->isYoungest())
-        return node.shadowHost()->shadow();
     if (isActiveInsertionPoint(*parent))
         return node.shadowHost()->shadow();
     if (parent->isElementNode())
diff --git a/engine/core/dom/shadow/ShadowRoot.cpp b/engine/core/dom/shadow/ShadowRoot.cpp
index df5ee773e4e..5875a449cd5 100644
--- a/engine/core/dom/shadow/ShadowRoot.cpp
+++ b/engine/core/dom/shadow/ShadowRoot.cpp
@@ -41,8 +41,8 @@
 
 namespace blink {
 
-struct SameSizeAsShadowRoot : public DocumentFragment, public TreeScope, public DoublyLinkedListNode<ShadowRoot> {
-    void* pointers[3];
+struct SameSizeAsShadowRoot : public DocumentFragment, public TreeScope {
+    void* pointers[1];
     unsigned countersAndFlags[1];
 };
 
@@ -51,8 +51,6 @@ COMPILE_ASSERT(sizeof(ShadowRoot) == sizeof(SameSizeAsShadowRoot), shadowroot_sh
 ShadowRoot::ShadowRoot(Document& document)
     : DocumentFragment(0, CreateShadowRoot)
     , TreeScope(*this, document)
-    , m_prev(nullptr)
-    , m_next(nullptr)
     , m_numberOfStyles(0)
     , m_registeredWithParentShadowRoot(false)
     , m_descendantInsertionPointsIsValid(false)
@@ -61,10 +59,6 @@ ShadowRoot::ShadowRoot(Document& document)
 
 ShadowRoot::~ShadowRoot()
 {
-#if !ENABLE(OILPAN)
-    ASSERT(!m_prev);
-    ASSERT(!m_next);
-
     if (m_shadowRootRareData && m_shadowRootRareData->styleSheets())
         m_shadowRootRareData->styleSheets()->detachFromDocument();
 
@@ -85,15 +79,12 @@ ShadowRoot::~ShadowRoot()
     // as well as Node. See a comment on TreeScope.h for the reason.
     if (hasRareData())
         clearRareData();
-#endif
 }
 
-#if !ENABLE(OILPAN)
 void ShadowRoot::dispose()
 {
     removeDetachedChildren();
 }
-#endif
 
 PassRefPtr<Node> ShadowRoot::cloneNode(bool, ExceptionState& exceptionState)
 {
@@ -130,7 +121,7 @@ void ShadowRoot::insertedInto(ContainerNode* insertionPoint)
 {
     DocumentFragment::insertedInto(insertionPoint);
 
-    if (!insertionPoint->inDocument() || !isOldest())
+    if (!insertionPoint->inDocument())
         return;
 
     // FIXME: When parsing <video controls>, insertedInto() is called many times without invoking removedFrom.
diff --git a/engine/core/dom/shadow/ShadowRoot.h b/engine/core/dom/shadow/ShadowRoot.h
index 2fc9907b3b6..e263f28db57 100644
--- a/engine/core/dom/shadow/ShadowRoot.h
+++ b/engine/core/dom/shadow/ShadowRoot.h
@@ -31,7 +31,6 @@
 #include "sky/engine/core/dom/DocumentFragment.h"
 #include "sky/engine/core/dom/Element.h"
 #include "sky/engine/core/dom/TreeScope.h"
-#include "sky/engine/wtf/DoublyLinkedList.h"
 
 namespace blink {
 
@@ -42,9 +41,8 @@ class InsertionPoint;
 class ShadowRootRareData;
 class StyleSheetList;
 
-class ShadowRoot final : public DocumentFragment, public TreeScope, public DoublyLinkedListNode<ShadowRoot> {
+class ShadowRoot final : public DocumentFragment, public TreeScope {
     DEFINE_WRAPPERTYPEINFO();
-    friend class WTF::DoublyLinkedListNode<ShadowRoot>;
 public:
 
     static PassRefPtr<ShadowRoot> create(Document& document)
@@ -61,12 +59,6 @@ public:
     Element* host() const { return toElement(parentOrShadowHostNode()); }
     ElementShadow* owner() const { return host() ? host()->shadow() : 0; }
 
-    ShadowRoot* youngerShadowRoot() const { return prev(); }
-
-    bool isYoungest() const { return !youngerShadowRoot(); }
-    bool isOldest() const { return !olderShadowRoot(); }
-    bool isOldestAuthorShadowRoot() const;
-
     virtual void insertedInto(ContainerNode*) override;
     virtual void removedFrom(ContainerNode*) override;
 
@@ -92,8 +84,6 @@ public:
 public:
     Element* activeElement() const;
 
-    ShadowRoot* olderShadowRoot() const { return next(); }
-
     PassRefPtr<Node> cloneNode(bool, ExceptionState&);
     PassRefPtr<Node> cloneNode(ExceptionState& exceptionState) { return cloneNode(true, exceptionState); }
 
@@ -116,11 +106,6 @@ private:
     // ShadowRoots should never be cloned.
     virtual PassRefPtr<Node> cloneNode(bool) override { return nullptr; }
 
-    // FIXME: This shouldn't happen. https://bugs.webkit.org/show_bug.cgi?id=88834
-    bool isOrphan() const { return !host(); }
-
-    RawPtr<ShadowRoot> m_prev;
-    RawPtr<ShadowRoot> m_next;
     OwnPtr<ShadowRootRareData> m_shadowRootRareData;
     unsigned m_numberOfStyles : 27;
     unsigned m_registeredWithParentShadowRoot : 1;
diff --git a/engine/core/dom/shadow/ShadowRoot.idl b/engine/core/dom/shadow/ShadowRoot.idl
index 04f8583b271..d052f549480 100644
--- a/engine/core/dom/shadow/ShadowRoot.idl
+++ b/engine/core/dom/shadow/ShadowRoot.idl
@@ -26,7 +26,6 @@
 
 interface ShadowRoot : DocumentFragment {
     readonly attribute Element activeElement;
-    readonly attribute ShadowRoot olderShadowRoot;
 
     [RaisesException] Node cloneNode([Default=Undefined] optional boolean deep);
     Selection getSelection();
diff --git a/engine/core/editing/TextIterator.cpp b/engine/core/editing/TextIterator.cpp
index a68f6c3196b..a2f878558d4 100644
--- a/engine/core/editing/TextIterator.cpp
+++ b/engine/core/editing/TextIterator.cpp
@@ -461,23 +461,12 @@ void TextIterator::advance()
                 }
 
                 if (!next && !parentNode && m_shadowDepth > 0) {
-                    // 4. Reached the top of a shadow root. If it's created by author, then try to visit the next
-                    // sibling shadow root, if any.
+                    // 4. Reached the top of a shadow root.
                     ShadowRoot* shadowRoot = toShadowRoot(m_node);
-                    ShadowRoot* nextShadowRoot = shadowRoot->olderShadowRoot();
-                    if (nextShadowRoot) {
-                        m_fullyClippedStack.pop();
-                        m_node = nextShadowRoot;
-                        m_iterationProgress = HandledNone;
-                        // m_shadowDepth is unchanged since we exit from a shadow root and enter another.
-                        pushFullyClippedState(m_fullyClippedStack, m_node);
-                    } else {
-                        // We are the last shadow root; exit from here and go back to where we were.
-                        m_node = shadowRoot->host();
-                        m_iterationProgress = HandledAuthorShadowRoots;
-                        --m_shadowDepth;
-                        m_fullyClippedStack.pop();
-                    }
+                    m_node = shadowRoot->host();
+                    m_iterationProgress = HandledAuthorShadowRoots;
+                    --m_shadowDepth;
+                    m_fullyClippedStack.pop();
                     continue;
                 }
             }
diff --git a/engine/core/events/EventPath.cpp b/engine/core/events/EventPath.cpp
index b1f4f84e5dc..cf1ef534db1 100644
--- a/engine/core/events/EventPath.cpp
+++ b/engine/core/events/EventPath.cpp
@@ -138,9 +138,9 @@ void EventPath::calculateTreeScopePrePostOrderNumbers()
     TreeScopeEventContext* rootTree = 0;
     for (size_t i = 0; i < m_treeScopeEventContexts.size(); ++i) {
         TreeScopeEventContext* treeScopeEventContext = m_treeScopeEventContexts[i].get();
-        // Use olderShadowRootOrParentTreeScope here for parent-child relationships.
+        // Use parentTreeScope here for parent-child relationships.
         // See the definition of trees of trees in the Shado DOM spec: http://w3c.github.io/webcomponents/spec/shadow/
-        TreeScope* parent = treeScopeEventContext->treeScope().olderShadowRootOrParentTreeScope();
+        TreeScope* parent = treeScopeEventContext->treeScope().parentTreeScope();
         if (!parent) {
             ASSERT(!rootTree);
             rootTree = treeScopeEventContext;
@@ -167,7 +167,7 @@ TreeScopeEventContext* EventPath::ensureTreeScopeEventContext(Node* currentTarge
         treeScopeEventContext = addResult.storedValue->value.get();
     }
     if (isNewEntry) {
-        TreeScopeEventContext* parentTreeScopeEventContext = ensureTreeScopeEventContext(0, treeScope->olderShadowRootOrParentTreeScope(), treeScopeEventContextMap);
+        TreeScopeEventContext* parentTreeScopeEventContext = ensureTreeScopeEventContext(0, treeScope->parentTreeScope(), treeScopeEventContextMap);
         if (parentTreeScopeEventContext && parentTreeScopeEventContext->target()) {
             treeScopeEventContext->setTarget(parentTreeScopeEventContext->target());
         } else if (currentTarget) {
@@ -219,7 +219,7 @@ EventTarget* EventPath::findRelatedNode(TreeScope* scope, RelatedTargetMap& rela
             relatedNode = iter->value;
             break;
         }
-        scope = scope->olderShadowRootOrParentTreeScope();
+        scope = scope->parentTreeScope();
     }
     ASSERT(relatedNode);
     for (Vector<RawPtr<TreeScope>, 32>::iterator iter = parentTreeScopes.begin(); iter < parentTreeScopes.end(); ++iter)
diff --git a/engine/core/page/FocusController.cpp b/engine/core/page/FocusController.cpp
index 00721a6acea..d13049947a1 100644
--- a/engine/core/page/FocusController.cpp
+++ b/engine/core/page/FocusController.cpp
@@ -96,7 +96,7 @@ FocusNavigationScope FocusNavigationScope::ownedByNonFocusableFocusScopeOwner(No
 FocusNavigationScope FocusNavigationScope::ownedByShadowHost(Node* node)
 {
     ASSERT(isShadowHost(node));
-    return FocusNavigationScope(toElement(node)->shadow()->youngestShadowRoot());
+    return FocusNavigationScope(toElement(node)->shadow()->shadowRoot());
 }
 
 static inline void dispatchEventsOnWindowAndFocusedNode(Document* document, bool focused)
diff --git a/engine/web/tests/data/touch-action-tests.js b/engine/web/tests/data/touch-action-tests.js
index 82265d5b91d..7eff011db1f 100644
--- a/engine/web/tests/data/touch-action-tests.js
+++ b/engine/web/tests/data/touch-action-tests.js
@@ -4,7 +4,7 @@ document.addEventListener('touchstart', function() {});
 window.addEventListener('load', function() {
   // Create any shadow DOM nodes requested by the test.
   var shadowTrees = document.querySelectorAll('[make-shadow-dom]');
-  if (shadowTrees.length > 0 && !HTMLElement.prototype.createShadowRoot) {
+  if (shadowTrees.length > 0 && !HTMLElement.prototype.ensureShadowRoot) {
     document.body.innerHTML = 'ERROR: Shadow DOM not supported!';
     return;
   }
@@ -16,7 +16,7 @@ window.addEventListener('load', function() {
       return;
     }
     tree.parentElement.removeChild(tree);
-    var shadowRoot = host.createShadowRoot();
+    var shadowRoot = host.ensureShadowRoot();
     shadowRoot.appendChild(tree);
   }
 });
diff --git a/framework/sky-element/sky-element.sky b/framework/sky-element/sky-element.sky
index 573c3545f62..81b796ae1fd 100644
--- a/framework/sky-element/sky-element.sky
+++ b/framework/sky-element/sky-element.sky
@@ -31,7 +31,7 @@ var BasePrototype = createPrototype(HTMLElement.prototype, {
     if (!this.shadowRoot) {
       var template = templates.get(this.localName);
       if (template) {
-        var shadow = this.createShadowRoot();
+        var shadow = this.ensureShadowRoot();
         shadow.appendChild(template.createInstance(this));
       }
     }
diff --git a/tests/dom/appendChild.sky b/tests/dom/appendChild.sky
index 60da8036d7f..e9025c9beb2 100644
--- a/tests/dom/appendChild.sky
+++ b/tests/dom/appendChild.sky
@@ -53,7 +53,7 @@ describe("appendChild", function() {
   it("should throw when inserting a tree scope", function() {
     var parent = document.createElement("div");
     var doc = new Document();
-    var shadowRoot = document.createElement("span").createShadowRoot();
+    var shadowRoot = document.createElement("span").ensureShadowRoot();
     assert.throws(function() {
       parent.appendChild(doc);
     });
diff --git a/tests/dom/replaceChild.sky b/tests/dom/replaceChild.sky
index 17cc7ad7bb2..bfa1d242620 100644
--- a/tests/dom/replaceChild.sky
+++ b/tests/dom/replaceChild.sky
@@ -67,7 +67,7 @@ describe("replaceChild", function() {
   it("should throw when inserting a tree scope", function() {
     var parent = document.createElement("div");
     var doc = new Document();
-    var shadowRoot = document.createElement("span").createShadowRoot();
+    var shadowRoot = document.createElement("span").ensureShadowRoot();
     assert.throws(function() {
       parent.replaceChild(doc);
     });
diff --git a/tests/mutation-observer/shadow-dom.sky b/tests/mutation-observer/shadow-dom.sky
index 43a20f6ba2a..f2d1f49b288 100644
--- a/tests/mutation-observer/shadow-dom.sky
+++ b/tests/mutation-observer/shadow-dom.sky
@@ -13,7 +13,7 @@ describe('MutationObservers', function() {
     }
 
     var range = document.getElementById('range');
-    var shadowRoot = range.createShadowRoot();
+    var shadowRoot = range.ensureShadowRoot();
     shadowRoot.appendChild(document.createElement('div'));
     var observer = new MutationObserver(function() { });