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

Source/core/html/canvas/WebGLSharedObject.cpp

Index: Source/core/html/canvas/WebGLSharedObject.cpp
diff --git a/Source/core/html/canvas/WebGLSharedObject.cpp b/Source/core/html/canvas/WebGLSharedObject.cpp
index 94f1db80baf915e4366e6a0ccc0777d42fe3e826..5d7ff411f9c4a44a09357214d16e18f391268964 100644
--- a/Source/core/html/canvas/WebGLSharedObject.cpp
+++ b/Source/core/html/canvas/WebGLSharedObject.cpp
@@ -40,8 +40,10 @@ WebGLSharedObject::WebGLSharedObject(WebGLRenderingContextBase* context)
 
 WebGLSharedObject::~WebGLSharedObject()
 {
+#if !ENABLE(OILPAN)

[sof, 2014/07/01 13:54:11]

If this object dies at the same time as its context group object (and,
transitively, all the rendering contexts that refer to it), then we do not
delete its underlying resource. The assumption is that the rendering context
will tear down all when finalized & it invoking destroyContext().

In all other cases, we assume that the disappearance of the rendering context
will detach the shared objects (via the context group object.)

     if (m_contextGroup)
         m_contextGroup->removeObject(this);
+#endif
 }
 
 void WebGLSharedObject::detachContextGroup()
@@ -50,7 +52,7 @@ void WebGLSharedObject::detachContextGroup()
     if (m_contextGroup) {
         deleteObject(0);
         m_contextGroup->removeObject(this);
-        m_contextGroup = 0;
+        m_contextGroup = nullptr;
     }
 }
 
@@ -59,4 +61,10 @@ blink::WebGraphicsContext3D* WebGLSharedObject::getAWebGraphicsContext3D() const
     return m_contextGroup ? m_contextGroup->getAWebGraphicsContext3D() : 0;
 }
 
+void WebGLSharedObject::trace(Visitor* visitor)
+{
+    visitor->trace(m_contextGroup);
+    WebGLObject::trace(visitor);
+}
+
 }