Add animation support for WebP images

Source/core/platform/image-decoders/ImageDecoder.cpp

 /*
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 128 matching lines @@
     info.addMember(m_data, "data");
     info.addMember(m_frameBufferCache, "frameBufferCache");
 }
 
 size_t ImageDecoder::clearCacheExceptFrame(size_t clearExceptFrame)
 {
     // Don't clear if there are no frames or only one frame.
     if (m_frameBufferCache.size() <= 1)
         return 0;
 
-    // We need to preserve frames such that:
-    //  1. We don't clear |clearExceptFrame|;
-    //  2. We don't clear any frame from which a future initFrameBuffer() call
-    //     will copy bitmap data.
-    // All other frames can be cleared.
-    while ((clearExceptFrame < m_frameBufferCache.size()) && (m_frameBufferCache[clearExceptFrame].status() == ImageFrame::FrameEmpty))
-        clearExceptFrame = m_frameBufferCache[clearExceptFrame].requiredPreviousFrameIndex();
-
     size_t frameBytesCleared = 0;
     for (size_t i = 0; i < m_frameBufferCache.size(); ++i) {
         if (i != clearExceptFrame) {
             frameBytesCleared += frameBytesAtIndex(i);
             clearFrameBuffer(i);
         }
     }
     return frameBytesCleared;
 }
 
@@ skipping 36 matching lines @@
         // Otherwise, the previous frame contributes to this frame.
         return (prevBuffer->originalFrameRect().contains(IntRect(IntPoint(), size()))
             || (prevBuffer->requiredPreviousFrameIndex() == notFound)) ? notFound : prevFrame;
     default:
         ASSERT_NOT_REACHED();
         return notFound;
     }
 }
 
 } // namespace WebCore