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

Source/core/html/canvas/WebGLContextObject.cpp

Index: Source/core/html/canvas/WebGLContextObject.cpp
diff --git a/Source/core/html/canvas/WebGLContextObject.cpp b/Source/core/html/canvas/WebGLContextObject.cpp
index 83441589defb70bea4690902c64c94840d3ce119..7d3612694d7f21ddd92f1cfee5b3bd6e803a8bcc 100644
--- a/Source/core/html/canvas/WebGLContextObject.cpp
+++ b/Source/core/html/canvas/WebGLContextObject.cpp
@@ -39,8 +39,10 @@ WebGLContextObject::WebGLContextObject(WebGLRenderingContextBase* context)
 
 WebGLContextObject::~WebGLContextObject()
 {
+#if !ENABLE(OILPAN)
     if (m_context)
         m_context->removeContextObject(this);
+#endif
 }
 
 void WebGLContextObject::detachContext()
@@ -49,13 +51,21 @@ void WebGLContextObject::detachContext()
     if (m_context) {
         deleteObject(m_context->webContext());
         m_context->removeContextObject(this);
-        m_context = 0;
+        m_context = nullptr;
     }
 }
 
+#if !ENABLE(OILPAN)
 blink::WebGraphicsContext3D* WebGLContextObject::getAWebGraphicsContext3D() const
 {
     return m_context ? m_context->webContext() : 0;
 }
+#endif
+
+void WebGLContextObject::trace(Visitor* visitor)
+{
+    visitor->trace(m_context);
+    WebGLObject::trace(visitor);
+}
 
 }