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..241035475a369126c297542f88ad5ca12a11fa68 100644
--- a/Source/core/html/canvas/WebGLSharedObject.cpp
+++ b/Source/core/html/canvas/WebGLSharedObject.cpp
@@ -50,13 +50,15 @@ void WebGLSharedObject::detachContextGroup()
     if (m_contextGroup) {
         deleteObject(0);
         m_contextGroup->removeObject(this);
-        m_contextGroup = 0;
+        m_contextGroup = nullptr;
     }
 }
 
+#if !ENABLE(OILPAN)
 blink::WebGraphicsContext3D* WebGLSharedObject::getAWebGraphicsContext3D() const
 {
     return m_contextGroup ? m_contextGroup->getAWebGraphicsContext3D() : 0;
 }
+#endif
 
 }