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)
     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);
+}
+
 }