Make the stocks popup menu fade in

The final animation is more involved, but this CL starts implementing the menu
animation by making it fade in.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1174253003.

engine/core/painting/Rect.cpp

@@ -22,6 +22,9 @@ Rect DartConverter<Rect>::FromArgumentsWithNullCheck(Dart_NativeArguments args,
   Dart_Handle dart_rect = Dart_GetNativeArgument(args, index);
   DCHECK(!LogIfError(dart_rect));
 
+  if (Dart_IsNull(dart_rect))
+    return result;
+
   Dart_Handle value =
       Dart_GetField(dart_rect, DOMDartState::Current()->value_handle());
   if (Dart_IsNull(value))

engine/platform/graphics/GraphicsContext.cpp.rej

@@ -1,22 +0,0 @@
---- platform/graphics/GraphicsContext.cpp
-+++ platform/graphics/GraphicsContext.cpp
-@@ -419,19 +419,6 @@
-     paint->setLCDRenderText(couldUseLCDRenderedText());
- }
- 
--bool GraphicsContext::couldUseLCDRenderedText() const
--{
--    ASSERT(m_canvas);
--    // Our layers only have a single alpha channel. This means that subpixel
--    // rendered text cannot be composited correctly when the layer is
--    // collapsed. Therefore, subpixel text is contextDisabled when we are drawing
--    // onto a layer.
--    if (contextDisabled() || m_canvas->isDrawingToLayer() || !isCertainlyOpaque())
--        return false;
--
--    return shouldSmoothFonts();
--}
--
- void GraphicsContext::setCompositeOperation(CompositeOperator compositeOperation, WebBlendMode blendMode)
- {
-     if (contextDisabled())

engine/platform/graphics/GraphicsContext.h.rej

@@ -1,15 +0,0 @@
---- platform/graphics/GraphicsContext.h
-+++ platform/graphics/GraphicsContext.h
-@@ -155,11 +155,10 @@
-     // FIXME: the setter is only used once, at construction time; convert to a constructor param,
-     // and possibly consolidate with other flags (paintDisabled, isPrinting, ...)
-     void setShouldSmoothFonts(bool smoothFonts) { m_shouldSmoothFonts = smoothFonts; }
--    bool shouldSmoothFonts() const { return m_shouldSmoothFonts; }
- 
-     // Turn off LCD text for the paint if not supported on this context.
-     void adjustTextRenderMode(SkPaint*) const;
--    bool couldUseLCDRenderedText() const;
-+    bool couldUseLCDRenderedText() const { return m_isCertainlyOpaque && m_shouldSmoothFonts; }
- 
-     void setTextDrawingMode(TextDrawingModeFlags mode) { mutableState()->setTextDrawingMode(mode); }
-     TextDrawingModeFlags textDrawingMode() const { return immutableState()->textDrawingMode(); }

sdk/lib/framework/components2/popup_menu.dart

@@ -114,14 +114,17 @@ class PopupMenu extends AnimatedComponent {
     }));
 
     // inlineStyle: _inlineStyle(),
-    return new ShrinkWrapWidth(
-      child: new Container(
-        padding: const EdgeDims.all(8.0),
-        decoration: new BoxDecoration(
-          backgroundColor: Grey[50],
-          borderRadius: 2.0,
-          boxShadow: Shadow[level]),
-        child: new Block(children)
+    return new Opacity(
+      opacity: math.min(1.0, _position * 3.0),
+      child: new ShrinkWrapWidth(
+        child: new Container(
+          padding: const EdgeDims.all(8.0),
+          decoration: new BoxDecoration(
+            backgroundColor: Grey[50],
+            borderRadius: 2.0,
+            boxShadow: Shadow[level]),
+          child: new Block(children)
+        )
       )
     );
   }

sdk/lib/framework/fn2.dart

@@ -378,6 +378,21 @@ abstract class OneChildRenderObjectWrapper extends RenderObjectWrapper {
 
 }
 
+class Opacity extends OneChildRenderObjectWrapper {
+  Opacity({ this.opacity, UINode child, Object key })
+    : super(child: child, key: key);
+
+  RenderOpacity get root { RenderOpacity result = super.root; return result; }
+  final double opacity;
+
+  RenderOpacity createNode() => new RenderOpacity(opacity: opacity);
+
+  void syncRenderObject(Opacity old) {
+    super.syncRenderObject(old);
+    root.opacity = opacity;
+  }
+}
+
 class ClipRect extends OneChildRenderObjectWrapper {
 
   ClipRect({ UINode child, Object key })

sdk/lib/framework/rendering/box.dart

@@ -439,6 +439,45 @@ class RenderShrinkWrapWidth extends RenderProxyBox {
   }
 }
 
+class RenderOpacity extends RenderProxyBox {
+  RenderOpacity({ RenderBox child, double opacity })
+    : this._opacity = opacity, super(child) {
+    assert(opacity >= 0.0 && opacity <= 1.0);
+  }
+
+  double _opacity;
+  double get opacity => _opacity;
+  void set opacity (double value) {
+    assert(value != null);
+    assert(value >= 0.0 && value <= 1.0);
+    if (_opacity == value)
+      return;
+    _opacity = value;
+    markNeedsPaint();
+  }
+
+  void paint(RenderObjectDisplayList canvas) {
+    if (child != null) {
+      int a = (_opacity * 255).round();
+
+      if (a == 0)
+        return;
+
+      if (a == 255) {
+        child.paint(canvas);
+        return;
+      }
+
+      Paint paint = new Paint()
+        ..color = new Color.fromARGB(a, 0, 0, 0)
+        ..setTransferMode(sky.TransferMode.srcOverMode);
+      canvas.saveLayer(null, paint);
+      child.paint(canvas);
+      canvas.restore();
+    }
+  }
+}
+
 class RenderClipRect extends RenderProxyBox {
   RenderClipRect({ RenderBox child }) : super(child);