diff --git a/sky/engine/bindings/BUILD.gn b/sky/engine/bindings/BUILD.gn
index 9883fbba9fe..0521277c2cb 100644
--- a/sky/engine/bindings/BUILD.gn
+++ b/sky/engine/bindings/BUILD.gn
@@ -9,10 +9,10 @@ source_set("bindings") {
   sources = [
     "builtin.cc",
     "builtin.h",
-    "builtin_natives.cc",
-    "builtin_natives.h",
-    "builtin_sky.cc",
-    "builtin_sky.h",
+    "dart_natives.cc",
+    "dart_natives.h",
+    "dart_ui.cc",
+    "dart_ui.h",
     "dart_callback.cc",
     "dart_callback.h",
     "exception_messages.cc",
@@ -62,7 +62,6 @@ action("generate_snapshot_bin") {
     "//mojo/public/dart/mojo/sdk_ext/src/handle_watcher.dart",
     "//mojo/public/dart/mojo/sdk_ext/src/natives.dart",
     "//mojo/public/dart/mojo/sdk_ext/src/timer_queue.dart",
-    "//sky/engine/bindings/builtin_natives.dart",
     "//sky/engine/bindings/internals.dart",
     "snapshot.dart",
   ]
@@ -75,8 +74,6 @@ action("generate_snapshot_bin") {
 
   dart_mojo_internal_path =
       rebase_path("//mojo/public/dart/mojo/sdk_ext/internal.dart")
-  dart_ui_builtin_natives_path =
-      rebase_path("//sky/engine/bindings/builtin_natives.dart")
   dart_ui_internals_path =
       rebase_path("//sky/engine/bindings/internals.dart")
   dart_ui_path = rebase_path("$bindings_output_dir/dart_ui.dart")
@@ -102,7 +99,6 @@ action("generate_snapshot_bin") {
     "--url_mapping=dart:mojo.internal,$dart_mojo_internal_path",
     "--url_mapping=dart:ui,$dart_ui_path",
     "--url_mapping=dart:ui_internals,$dart_ui_internals_path",
-    "--url_mapping=dart:ui_builtin_natives,$dart_ui_builtin_natives_path",
   ]
 }
 
diff --git a/sky/engine/bindings/builtin.cc b/sky/engine/bindings/builtin.cc
index dcaf6e1c57c..eebef4ecd5f 100644
--- a/sky/engine/bindings/builtin.cc
+++ b/sky/engine/bindings/builtin.cc
@@ -7,9 +7,8 @@
 #include "base/logging.h"
 #include "bin/io_natives.h"
 #include "dart/runtime/include/dart_api.h"
-#include "gen/sky/bindings/DartGlobal.h"
-#include "sky/engine/bindings/builtin_natives.h"
-#include "sky/engine/bindings/builtin_sky.h"
+#include "sky/engine/bindings/dart_natives.h"
+#include "sky/engine/bindings/dart_ui.h"
 #include "sky/engine/bindings/mojo_natives.h"
 #include "sky/engine/tonic/dart_builtin.h"
 
@@ -25,11 +24,7 @@ struct LibraryDescriptor {
 
 const LibraryDescriptor kBuiltinLibraries[] = {
     /* { url_, has_natives_, native_symbol_, native_resolver_ } */
-    {"dart:ui_builtin_natives",
-     true,
-     BuiltinNatives::NativeSymbol,
-     BuiltinNatives::NativeLookup},
-    {"dart:ui", true, skySnapshotSymbolizer, skySnapshotResolver},
+    {"dart:ui", true, DartUI::NativeSymbol, DartUI::NativeLookup},
     {"dart:mojo.internal", true, MojoNativeSymbol, MojoNativeLookup},
     {"dart:io", true, dart::bin::IONativeSymbol, dart::bin::IONativeLookup },
 };
@@ -39,7 +34,7 @@ const LibraryDescriptor kBuiltinLibraries[] = {
 void Builtin::SetNativeResolver(BuiltinLibraryId id) {
   static_assert(arraysize(kBuiltinLibraries) == kInvalidLibrary,
       "Unexpected number of builtin libraries");
-  DCHECK_GE(id, kBuiltinLibrary);
+  DCHECK_GE(id, kUILibrary);
   DCHECK_LT(id, kInvalidLibrary);
   if (kBuiltinLibraries[id].has_natives) {
     Dart_Handle library = DartBuiltin::LookupLibrary(kBuiltinLibraries[id].url);
@@ -54,7 +49,7 @@ void Builtin::SetNativeResolver(BuiltinLibraryId id) {
 Dart_Handle Builtin::LoadAndCheckLibrary(BuiltinLibraryId id) {
   static_assert(arraysize(kBuiltinLibraries) == kInvalidLibrary,
       "Unexpected number of builtin libraries");
-  DCHECK_GE(id, kBuiltinLibrary);
+  DCHECK_GE(id, kUILibrary);
   DCHECK_LT(id, kInvalidLibrary);
   Dart_Handle library = DartBuiltin::LookupLibrary(kBuiltinLibraries[id].url);
   DART_CHECK_VALID(library);
diff --git a/sky/engine/bindings/builtin.h b/sky/engine/bindings/builtin.h
index 93f67a258e2..b004fe8ffdd 100644
--- a/sky/engine/bindings/builtin.h
+++ b/sky/engine/bindings/builtin.h
@@ -15,8 +15,7 @@ class Builtin {
   // Note: Changes to this enum should be accompanied with changes to
   // the builtin_libraries_ array in builtin.cc.
   enum BuiltinLibraryId {
-    kBuiltinLibrary,
-    kSkyLibrary,
+    kUILibrary,
     kMojoInternalLibrary,
     kIOLibrary,
     kInvalidLibrary,
diff --git a/sky/engine/bindings/builtin_sky.cc b/sky/engine/bindings/builtin_sky.cc
deleted file mode 100644
index 7ccd266bc3e..00000000000
--- a/sky/engine/bindings/builtin_sky.cc
+++ /dev/null
@@ -1,35 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sky/engine/bindings/builtin_sky.h"
-
-#include "sky/engine/bindings/builtin.h"
-#include "sky/engine/core/frame/LocalDOMWindow.h"
-#include "sky/engine/core/script/dom_dart_state.h"
-#include "sky/engine/core/view/View.h"
-#include "sky/engine/tonic/dart_error.h"
-
-namespace blink {
-
-BuiltinSky::BuiltinSky(DOMDartState* dart_state) {
-  Builtin::SetNativeResolver(Builtin::kSkyLibrary);
-  library_.Set(dart_state, Builtin::LoadAndCheckLibrary(Builtin::kSkyLibrary));
-}
-
-BuiltinSky::~BuiltinSky() {
-}
-
-void BuiltinSky::InstallView(View* view) {
-  CHECK(!LogIfError(
-      Dart_SetField(library_.value(), ToDart("view"), ToDart(view))));
-}
-
-Dart_Handle BuiltinSky::GetClassByName(const char* class_name) {
-  Dart_Handle name_handle = ToDart(class_name);
-  Dart_Handle class_handle = Dart_GetType(library_.value(), name_handle, 0, nullptr);
-  DCHECK(!Dart_IsError(class_handle)) << class_name;
-  return class_handle;
-}
-
-}  // namespace blink
diff --git a/sky/engine/bindings/builtin_natives.cc b/sky/engine/bindings/dart_natives.cc
similarity index 91%
rename from sky/engine/bindings/builtin_natives.cc
rename to sky/engine/bindings/dart_natives.cc
index 7084b8446ff..574f9fe0ec5 100644
--- a/sky/engine/bindings/builtin_natives.cc
+++ b/sky/engine/bindings/dart_natives.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "sky/engine/bindings/builtin_natives.h"
+#include "sky/engine/bindings/dart_natives.h"
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -61,7 +61,7 @@ static struct NativeEntries {
   int argument_count;
 } BuiltinEntries[] = {BUILTIN_NATIVE_LIST(REGISTER_FUNCTION)};
 
-Dart_NativeFunction BuiltinNatives::NativeLookup(Dart_Handle name,
+Dart_NativeFunction DartNatives::NativeLookup(Dart_Handle name,
                                                  int argument_count,
                                                  bool* auto_setup_scope) {
   const char* function_name = nullptr;
@@ -81,7 +81,7 @@ Dart_NativeFunction BuiltinNatives::NativeLookup(Dart_Handle name,
   return nullptr;
 }
 
-const uint8_t* BuiltinNatives::NativeSymbol(Dart_NativeFunction native_function) {
+const uint8_t* DartNatives::NativeSymbol(Dart_NativeFunction native_function) {
   size_t num_entries = arraysize(BuiltinEntries);
   for (size_t i = 0; i < num_entries; i++) {
     const struct NativeEntries& entry = BuiltinEntries[i];
@@ -100,7 +100,7 @@ static Dart_Handle GetClosure(Dart_Handle builtin_library, const char* name) {
 }
 
 static void InitDartInternal(Dart_Handle builtin_library,
-                             BuiltinNatives::IsolateType isolate_type) {
+                             DartNatives::IsolateType isolate_type) {
   Dart_Handle print = GetClosure(builtin_library, "_getPrintClosure");
   Dart_Handle timer = GetClosure(builtin_library, "_getCreateTimerClosure");
 
@@ -109,14 +109,14 @@ static void InitDartInternal(Dart_Handle builtin_library,
   DART_CHECK_VALID(Dart_SetField(
       internal_library, ToDart("_printClosure"), print));
 
-  if (isolate_type == BuiltinNatives::MainIsolate) {
+  if (isolate_type == DartNatives::MainIsolate) {
     Dart_Handle vm_hooks_name = ToDart("VMLibraryHooks");
     Dart_Handle vm_hooks = Dart_GetClass(internal_library, vm_hooks_name);
     DART_CHECK_VALID(vm_hooks);
     Dart_Handle timer_name = ToDart("timerFactory");
     DART_CHECK_VALID(Dart_SetField(vm_hooks, timer_name, timer));
   } else {
-    CHECK(isolate_type == BuiltinNatives::DartIOIsolate);
+    CHECK(isolate_type == DartNatives::DartIOIsolate);
     Dart_Handle io_lib = DartBuiltin::LookupLibrary("dart:io");
     Dart_Handle setup_hooks = Dart_NewStringFromCString("_setupHooks");
     DART_CHECK_VALID(Dart_Invoke(io_lib, setup_hooks, 0, NULL));
@@ -126,7 +126,7 @@ static void InitDartInternal(Dart_Handle builtin_library,
 }
 
 static void InitDartCore(Dart_Handle builtin,
-                         BuiltinNatives::IsolateType isolate_type) {
+                         DartNatives::IsolateType isolate_type) {
   Dart_Handle get_base_url = GetClosure(builtin, "_getGetBaseURLClosure");
   Dart_Handle core_library = DartBuiltin::LookupLibrary("dart:core");
   DART_CHECK_VALID(Dart_SetField(core_library,
@@ -134,13 +134,13 @@ static void InitDartCore(Dart_Handle builtin,
 }
 
 static void InitDartAsync(Dart_Handle builtin_library,
-                          BuiltinNatives::IsolateType isolate_type) {
+                          DartNatives::IsolateType isolate_type) {
   Dart_Handle schedule_microtask;
-  if (isolate_type == BuiltinNatives::MainIsolate) {
+  if (isolate_type == DartNatives::MainIsolate) {
     schedule_microtask =
         GetClosure(builtin_library, "_getScheduleMicrotaskClosure");
   } else {
-    CHECK(isolate_type == BuiltinNatives::DartIOIsolate);
+    CHECK(isolate_type == DartNatives::DartIOIsolate);
     Dart_Handle isolate_lib = DartBuiltin::LookupLibrary("dart:isolate");
     Dart_Handle method_name =
         Dart_NewStringFromCString("_getIsolateScheduleImmediateClosure");
@@ -152,8 +152,8 @@ static void InitDartAsync(Dart_Handle builtin_library,
                                &schedule_microtask));
 }
 
-void BuiltinNatives::Init(IsolateType isolate_type) {
-  Dart_Handle builtin = Builtin::LoadAndCheckLibrary(Builtin::kBuiltinLibrary);
+void DartNatives::Init(IsolateType isolate_type) {
+  Dart_Handle builtin = Builtin::LoadAndCheckLibrary(Builtin::kUILibrary);
   DART_CHECK_VALID(builtin);
   InitDartInternal(builtin, isolate_type);
   InitDartCore(builtin, isolate_type);
diff --git a/sky/engine/bindings/builtin_natives.h b/sky/engine/bindings/dart_natives.h
similarity index 75%
rename from sky/engine/bindings/builtin_natives.h
rename to sky/engine/bindings/dart_natives.h
index 3f525bc8e64..0dd1e8c2a73 100644
--- a/sky/engine/bindings/builtin_natives.h
+++ b/sky/engine/bindings/dart_natives.h
@@ -2,15 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef SKY_ENGINE_BINDINGS_BUILTIN_NATIVES_H_
-#define SKY_ENGINE_BINDINGS_BUILTIN_NATIVES_H_
+#ifndef SKY_ENGINE_BINDINGS_DART_NATIVES_H_
+#define SKY_ENGINE_BINDINGS_DART_NATIVES_H_
 
 #include "base/macros.h"
 #include "dart/runtime/include/dart_api.h"
 
 namespace blink {
 
-class BuiltinNatives {
+class DartNatives {
  public:
   enum IsolateType {
     MainIsolate,
@@ -25,9 +25,9 @@ class BuiltinNatives {
   static void Init(IsolateType isolate_type);
 
  private:
-  DISALLOW_IMPLICIT_CONSTRUCTORS(BuiltinNatives);
+  DISALLOW_IMPLICIT_CONSTRUCTORS(DartNatives);
 };
 
 }  // namespace blink
 
-#endif  // SKY_ENGINE_BINDINGS_BUILTIN_NATIVES_H_
+#endif  // SKY_ENGINE_BINDINGS_DART_NATIVES_H_
diff --git a/sky/engine/bindings/dart_ui.cc b/sky/engine/bindings/dart_ui.cc
new file mode 100644
index 00000000000..5479ce2a3af
--- /dev/null
+++ b/sky/engine/bindings/dart_ui.cc
@@ -0,0 +1,50 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "sky/engine/bindings/dart_ui.h"
+
+#include "gen/sky/bindings/DartGlobal.h"
+#include "sky/engine/bindings/builtin.h"
+#include "sky/engine/bindings/dart_natives.h"
+#include "sky/engine/core/frame/LocalDOMWindow.h"
+#include "sky/engine/core/script/dom_dart_state.h"
+#include "sky/engine/core/view/View.h"
+#include "sky/engine/tonic/dart_error.h"
+
+namespace blink {
+
+DartUI::DartUI(DOMDartState* dart_state) {
+  library_.Set(dart_state, Builtin::LoadAndCheckLibrary(Builtin::kUILibrary));
+}
+
+DartUI::~DartUI() {
+}
+
+Dart_NativeFunction DartUI::NativeLookup(Dart_Handle name,
+                                         int argument_count,
+                                         bool* auto_setup_scope) {
+  if (auto result = DartNatives::NativeLookup(name, argument_count, auto_setup_scope))
+    return result;
+  return skySnapshotResolver(name, argument_count, auto_setup_scope);
+}
+
+const uint8_t* DartUI::NativeSymbol(Dart_NativeFunction native_function) {
+  if (auto result = DartNatives::NativeSymbol(native_function))
+    return result;
+  return skySnapshotSymbolizer(native_function);
+}
+
+void DartUI::InstallView(View* view) {
+  CHECK(!LogIfError(
+      Dart_SetField(library_.value(), ToDart("view"), ToDart(view))));
+}
+
+Dart_Handle DartUI::GetClassByName(const char* class_name) {
+  Dart_Handle name_handle = ToDart(class_name);
+  Dart_Handle class_handle = Dart_GetType(library_.value(), name_handle, 0, nullptr);
+  DCHECK(!Dart_IsError(class_handle)) << class_name;
+  return class_handle;
+}
+
+}  // namespace blink
diff --git a/sky/engine/bindings/builtin_sky.h b/sky/engine/bindings/dart_ui.h
similarity index 53%
rename from sky/engine/bindings/builtin_sky.h
rename to sky/engine/bindings/dart_ui.h
index 25bdcbd5b91..fffbe4eaa20 100644
--- a/sky/engine/bindings/builtin_sky.h
+++ b/sky/engine/bindings/dart_ui.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef SKY_ENGINE_BINDINGS_BUILTIN_SKY_H_
-#define SKY_ENGINE_BINDINGS_BUILTIN_SKY_H_
+#ifndef SKY_ENGINE_BINDINGS_DART_UI_H_
+#define SKY_ENGINE_BINDINGS_DART_UI_H_
 
 #include "base/macros.h"
 #include "dart/runtime/include/dart_api.h"
@@ -14,10 +14,15 @@ namespace blink {
 class DOMDartState;
 class View;
 
-class BuiltinSky : public DartClassProvider {
+class DartUI : public DartClassProvider {
  public:
-  explicit BuiltinSky(DOMDartState* dart_state);
-  ~BuiltinSky();
+  explicit DartUI(DOMDartState* dart_state);
+  ~DartUI();
+
+  static Dart_NativeFunction NativeLookup(Dart_Handle name,
+                                          int argument_count,
+                                          bool* auto_setup_scope);
+  static const uint8_t* NativeSymbol(Dart_NativeFunction native_function);
 
   void InstallView(View* view);
 
@@ -27,9 +32,9 @@ class BuiltinSky : public DartClassProvider {
  private:
   DartPersistentValue library_;
 
-  DISALLOW_COPY_AND_ASSIGN(BuiltinSky);
+  DISALLOW_COPY_AND_ASSIGN(DartUI);
 };
 
 }  // namespace blink
 
-#endif  // SKY_ENGINE_BINDINGS_BUILTIN_SKY_H_
+#endif  // SKY_ENGINE_BINDINGS_DART_UI_H_
diff --git a/sky/engine/bindings/scripts/templates/dart_blink.template b/sky/engine/bindings/scripts/templates/dart_blink.template
index 3388fe25170..0717b6584ff 100644
--- a/sky/engine/bindings/scripts/templates/dart_blink.template
+++ b/sky/engine/bindings/scripts/templates/dart_blink.template
@@ -6,6 +6,7 @@
 // WARNING: Do not edit - generated code.
 library dart_ui;
 
+import 'dart:async';
 import 'dart:nativewrappers';
 import 'dart:typed_data';
 import 'dart:math' as math;
diff --git a/sky/engine/bindings/snapshot.dart b/sky/engine/bindings/snapshot.dart
index 55fffdefac7..a4898b5151e 100644
--- a/sky/engine/bindings/snapshot.dart
+++ b/sky/engine/bindings/snapshot.dart
@@ -13,5 +13,4 @@ import 'dart:mojo.internal';
 import 'dart:mirrors';
 import 'dart:ui';
 import 'dart:ui_internals';
-import 'dart:ui_builtin_natives';
 import 'dart:typed_data';
diff --git a/sky/engine/core/core.gni b/sky/engine/core/core.gni
index 6d00ee10975..bfba38d8835 100644
--- a/sky/engine/core/core.gni
+++ b/sky/engine/core/core.gni
@@ -676,6 +676,7 @@ core_idl_files = get_path_info([
 
 core_dart_files = get_path_info([
                                   "dart/hooks.dart",
+                                  "dart/natives.dart",
                                   "dart/lerp.dart",
                                   "dart/view.dart",
                                   "dart/window.dart",
diff --git a/sky/engine/bindings/builtin_natives.dart b/sky/engine/core/dart/natives.dart
similarity index 96%
rename from sky/engine/bindings/builtin_natives.dart
rename to sky/engine/core/dart/natives.dart
index fa689a7745b..0a9e8b43b04 100644
--- a/sky/engine/bindings/builtin_natives.dart
+++ b/sky/engine/core/dart/natives.dart
@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-library builtin_natives;
-
-import "dart:async";
+part of dart_ui;
 
 // Corelib 'print' implementation.
 void _print(arg) {
diff --git a/sky/engine/core/script/dart_controller.cc b/sky/engine/core/script/dart_controller.cc
index 94c7be9bd61..562926f1bc7 100644
--- a/sky/engine/core/script/dart_controller.cc
+++ b/sky/engine/core/script/dart_controller.cc
@@ -12,8 +12,8 @@
 #include "mojo/data_pipe_utils/data_pipe_utils.h"
 #include "mojo/public/cpp/system/data_pipe.h"
 #include "sky/engine/bindings/builtin.h"
-#include "sky/engine/bindings/builtin_natives.h"
-#include "sky/engine/bindings/builtin_sky.h"
+#include "sky/engine/bindings/dart_natives.h"
+#include "sky/engine/bindings/dart_ui.h"
 #include "sky/engine/core/script/dart_debugger.h"
 #include "sky/engine/core/script/dart_init.h"
 #include "sky/engine/core/script/dart_service_isolate.h"
@@ -147,13 +147,13 @@ void DartController::CreateIsolateFor(PassOwnPtr<DOMDartState> state) {
   {
     DartApiScope apiScope;
 
-    Builtin::SetNativeResolver(Builtin::kBuiltinLibrary);
+    Builtin::SetNativeResolver(Builtin::kUILibrary);
     Builtin::SetNativeResolver(Builtin::kMojoInternalLibrary);
     Builtin::SetNativeResolver(Builtin::kIOLibrary);
-    BuiltinNatives::Init(BuiltinNatives::MainIsolate);
+    DartNatives::Init(DartNatives::MainIsolate);
 
-    builtin_sky_ = adoptPtr(new BuiltinSky(dart_state()));
-    dart_state()->class_library().set_provider(builtin_sky_.get());
+    dart_ui_ = adoptPtr(new DartUI(dart_state()));
+    dart_state()->class_library().set_provider(dart_ui_.get());
 
     EnsureHandleWatcherStarted();
   }
@@ -164,7 +164,7 @@ void DartController::InstallView(View* view) {
   DartIsolateScope isolate_scope(dart_state()->isolate());
   DartApiScope dart_api_scope;
 
-  builtin_sky_->InstallView(view);
+  dart_ui_->InstallView(view);
 }
 
 static void DartController_DartStreamConsumer(
diff --git a/sky/engine/core/script/dart_controller.h b/sky/engine/core/script/dart_controller.h
index e7580899327..98e953bbc08 100644
--- a/sky/engine/core/script/dart_controller.h
+++ b/sky/engine/core/script/dart_controller.h
@@ -16,7 +16,7 @@
 
 namespace blink {
 class AbstractModule;
-class BuiltinSky;
+class DartUI;
 class DOMDartState;
 class DartLibraryProvider;
 class DartSnapshotLoader;
@@ -50,7 +50,7 @@ class DartController {
   void DidLoadSnapshot();
 
   OwnPtr<DOMDartState> dom_dart_state_;
-  OwnPtr<BuiltinSky> builtin_sky_;
+  OwnPtr<DartUI> dart_ui_;
   OwnPtr<DartSnapshotLoader> snapshot_loader_;
 
   base::WeakPtrFactory<DartController> weak_factory_;
diff --git a/sky/engine/core/script/dart_init.cc b/sky/engine/core/script/dart_init.cc
index 3a5935a0b5b..8189059b3fe 100644
--- a/sky/engine/core/script/dart_init.cc
+++ b/sky/engine/core/script/dart_init.cc
@@ -12,8 +12,8 @@
 #include "dart/runtime/include/dart_mirrors_api.h"
 #include "gen/sky/platform/RuntimeEnabledFeatures.h"
 #include "sky/engine/bindings/builtin.h"
-#include "sky/engine/bindings/builtin_natives.h"
-#include "sky/engine/bindings/builtin_sky.h"
+#include "sky/engine/bindings/dart_natives.h"
+#include "sky/engine/bindings/dart_ui.h"
 #include "sky/engine/core/script/dart_debugger.h"
 #include "sky/engine/core/script/dart_service_isolate.h"
 #include "sky/engine/core/script/dom_dart_state.h"
@@ -121,10 +121,10 @@ Dart_Isolate IsolateCreateCallback(const char* script_uri,
     CHECK(!LogIfError(Dart_SetLibraryTagHandler(DartLibraryTagHandler)));
     {
       DartApiScope apiScope;
-      Builtin::SetNativeResolver(Builtin::kBuiltinLibrary);
+      Builtin::SetNativeResolver(Builtin::kUILibrary);
       Builtin::SetNativeResolver(Builtin::kMojoInternalLibrary);
       Builtin::SetNativeResolver(Builtin::kIOLibrary);
-      BuiltinNatives::Init(BuiltinNatives::DartIOIsolate);
+      DartNatives::Init(DartNatives::DartIOIsolate);
       // Start the handle watcher from the service isolate so it isn't available
       // for debugging or general Observatory interaction.
       EnsureHandleWatcherStarted();
@@ -154,7 +154,7 @@ Dart_Isolate IsolateCreateCallback(const char* script_uri,
 
   {
     DartApiScope apiScope;
-    Builtin::SetNativeResolver(Builtin::kBuiltinLibrary);
+    Builtin::SetNativeResolver(Builtin::kUILibrary);
     Builtin::SetNativeResolver(Builtin::kMojoInternalLibrary);
     Builtin::SetNativeResolver(Builtin::kIOLibrary);
 
diff --git a/sky/packages/sky_engine/BUILD.gn b/sky/packages/sky_engine/BUILD.gn
index b71bcc50e2b..c27cb30cb86 100644
--- a/sky/packages/sky_engine/BUILD.gn
+++ b/sky/packages/sky_engine/BUILD.gn
@@ -49,11 +49,9 @@ dart_pkg("sky_engine") {
   sdk_ext_directory = "$root_gen_dir/sky/bindings"
   sdk_ext_files = [
     "//sky/engine/bindings/internals.dart",
-    "//sky/engine/bindings/builtin_natives.dart",
   ]
   sdk_ext_mappings = [
     "dart:ui,dart_ui.dart",
     "dart:ui_internals,internals.dart",
-    "dart:ui_builtin_natives,builtin_natives.dart",
   ]
 }
diff --git a/sky/tools/skypy/url_mappings.py b/sky/tools/skypy/url_mappings.py
index 6de007ead45..4e6a3740667 100644
--- a/sky/tools/skypy/url_mappings.py
+++ b/sky/tools/skypy/url_mappings.py
@@ -10,7 +10,6 @@ class URLMappings(object):
             'dart:mojo.internal': os.path.join(src_root, 'mojo/public/dart/sdk_ext/internal.dart'),
             'dart:ui': os.path.join(build_dir, 'gen/sky/bindings/dart_ui.dart'),
             'dart:ui_internals': os.path.join(src_root, 'sky/engine/bindings/internals.dart'),
-            'dart:ui_builtin_natives': os.path.join(src_root, 'sky/engine/bindings/builtin_natives.dart'),
         }
         self.packages_root = os.path.join(build_dir, 'gen/dart-pkg/packages')