Inflate rect instead of m_dirtyRect in HTMLCanvasElement::didDraw

third_party/WebKit/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 251 matching lines @@
 }
 
 void HTMLCanvasElement::didDraw(const FloatRect& rect)
 {
     if (rect.isEmpty())
         return;
     m_imageBufferIsClear = false;
     clearCopiedImage();
     if (layoutObject())
         layoutObject()->setMayNeedPaintInvalidation();
-    m_dirtyRect.unite(rect);
-    if (m_context && m_context->is2d() && m_context->shouldAntialias() && page() && page()->deviceScaleFactor() > 1.0f)
-        m_dirtyRect.inflate(1);
+    if (m_context && m_context->is2d() && m_context->shouldAntialias() && page() && page()->deviceScaleFactor() > 1.0f) {
+        FloatRect inflatedRect = rect;
+        inflatedRect.inflate(1);
+        m_dirtyRect.unite(inflatedRect);
+    } else {
+        m_dirtyRect.unite(rect);
+    }
     if (m_context && m_context->is2d() && hasImageBuffer())
         buffer()->didDraw(rect);
 }
 
 void HTMLCanvasElement::didFinalizeFrame()
 {
     notifyListenersCanvasChanged();
 
     if (m_dirtyRect.isEmpty())
         return;
@@ skipping 841 matching lines @@
 }
 
 String HTMLCanvasElement::getIdFromControl(const Element* element)
 {
     if (m_context)
         return m_context->getIdFromControl(element);
     return String();
 }
 
 } // namespace blink