Oilpan: move 2D Canvas and WebGL objects to the heap.

Source/core/html/canvas/CanvasContextAttributes.h

Index: Source/core/html/canvas/CanvasContextAttributes.h
diff --git a/Source/core/html/canvas/CanvasContextAttributes.h b/Source/core/html/canvas/CanvasContextAttributes.h
index afa8df892ee4cf80cb889c5820b3ba74c072ea12..c9f3da880fff422995cd3ad8b550112921415dd6 100644
--- a/Source/core/html/canvas/CanvasContextAttributes.h
+++ b/Source/core/html/canvas/CanvasContextAttributes.h
@@ -27,6 +27,7 @@
 #ifndef CanvasContextAttributes_h
 #define CanvasContextAttributes_h
 
+#include "platform/heap/Handle.h"
 #include "wtf/RefCounted.h"
 
 namespace blink {
@@ -34,11 +35,12 @@ namespace blink {
 // A base class for any attributes that are needed which would affect
 // the creation of the Canvas's rendering context.
 
-class CanvasContextAttributes : public RefCounted<CanvasContextAttributes> {
-  public:
-    virtual ~CanvasContextAttributes();
+class CanvasContextAttributes : public RefCountedWillBeGarbageCollectedFinalized<CanvasContextAttributes> {
+    DECLARE_EMPTY_VIRTUAL_DESTRUCTOR_WILL_BE_REMOVED(CanvasContextAttributes);
+public:
+    virtual void trace(Visitor*) { }
 
-  protected:
+protected:
     CanvasContextAttributes();
 };