Track scissored damage area for WebGL

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 309 matching lines @@
     setSurfaceSize(newSize);
 
     if (m_context && m_context->is3d() && oldSize != size())
         toWebGLRenderingContext(m_context.get())->reshape(width(), height());
 
     if (RenderObject* renderer = this->renderer()) {
         if (renderer->isCanvas()) {
             if (oldSize != size()) {
                 toRenderHTMLCanvas(renderer)->canvasSizeChanged();
                 if (renderBox() && renderBox()->hasAcceleratedCompositing())
-                    renderBox()->contentChanged(CanvasChanged);
+                    renderBox()->contentChanged(CanvasChanged, IntRect(IntPoint(0, 0), size()));
             }
             if (hadImageBuffer)
                 renderer->setShouldDoFullPaintInvalidation();
         }
     }
 
     for (CanvasObserver* canvasObserver : m_observers)
         canvasObserver->canvasResized(this);
 }
 
@@ skipping 442 matching lines @@
 {
     return !originClean();
 }
 
 FloatSize HTMLCanvasElement::sourceSize() const
 {
     return FloatSize(width(), height());
 }
 
 }