Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/html/canvas/WebGLRenderingContextBase.cpp

 /*
  * Copyright (C) 2009 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 683 matching lines @@
     // release all extensions
     for (size_t i = 0; i < m_extensions.size(); ++i)
         delete m_extensions[i];
 
     // Context must be removed from the group prior to the destruction of the
     // WebGraphicsContext3D, otherwise shared objects may not be properly deleted.
     m_contextGroup->removeContext(this);
 
     destroyContext();
 
+#if !ENABLE(OILPAN)
     if (m_multisamplingObserverRegistered) {
         Page* page = canvas()->document().page();
         if (page)
             page->removeMultisamplingChangedObserver(this);
     }
+#endif
 
     willDestroyContext(this);
 }
 
 void WebGLRenderingContextBase::destroyContext()
 {
     m_contextLost = true;
 
     if (!m_drawingBuffer)
         return;
@@ skipping 4948 matching lines @@
         if (m_textureUnits[i].m_texture2DBinding
             || m_textureUnits[i].m_textureCubeMapBinding) {
             m_onePlusMaxNonDefaultTextureUnit = i + 1;
             return;
         }
     }
     m_onePlusMaxNonDefaultTextureUnit = 0;
 }
 
 } // namespace WebCore