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

Source/core/html/canvas/WebGLContextGroup.h

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 40 matching lines @@
     void addContext(WebGLRenderingContextBase*);
     void removeContext(WebGLRenderingContextBase*);
 
     void addObject(WebGLSharedObject*);
     void removeObject(WebGLSharedObject*);
 
     blink::WebGraphicsContext3D* getAWebGraphicsContext3D();
 
     void loseContextGroup(WebGLRenderingContextBase::LostContextMode);
 
-  private:
+private:
     friend class WebGLObject;
 
     WebGLContextGroup();
 
     void detachAndRemoveAllObjects();
 
+    // FIXME: Oilpan: this object is not on the heap, but keeps bare
+    // pointers to garbage collected objects in the two hash sets
+    // below. The objects are responsible for managing their
+    // registration with WebGLContextGroup, and vice versa, the
+    // WebGLContextGroup takes care of detaching the group objects if
+    // the set of WebGLRenderingContextBase contexts becomes empty.
     HashSet<WebGLRenderingContextBase*> m_contexts;
     HashSet<WebGLSharedObject*> m_groupObjects;
 };
 
 } // namespace WebCore
 
 #endif // WebGLContextGroup_h