Remove some orphaned USE macros.

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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.
@@ skipping 282 matching lines @@
 #if ENABLE(HIGH_DPI_CANVAS)
     return document()->frame() ? document()->frame()->page()->deviceScaleFactor() : 1;
 #else
     return 1;
 #endif
 }
 
 bool HTMLCanvasElement::paintsIntoCanvasBuffer() const
 {
     ASSERT(m_context);
-#if USE(IOSURFACE_CANVAS_BACKING_STORE)
-    if (m_context->is2d())
-        return true;
-#endif
 
     if (!m_context->isAccelerated())
         return true;
 
     if (renderBox() && renderBox()->hasAcceleratedCompositing())
         return false;
 
     return true;
 }
 
@@ skipping 272 matching lines @@
     HTMLElement::reportMemoryUsage(memoryObjectInfo);
     info.addMember(m_observers, "observers");
     info.addMember(m_context, "context");
     info.addMember(m_imageBuffer, "imageBuffer");
     info.addMember(m_contextStateSaver, "contextStateSaver");
     info.addMember(m_presentedImage, "presentedImage");
     info.addMember(m_copiedImage, "copiedImage");
 }
 
 }