Add animation support for WebP images

Source/core/platform/image-decoders/gif/GIFImageDecoder.cpp

 /*
  * Copyright (C) 2006 Apple Computer, 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 287 matching lines @@
     if (failed())
         return;
 
     Vector<size_t> framesToDecode;
     size_t frameToDecode = frameIndex;
     do {
         framesToDecode.append(frameToDecode);
         frameToDecode = m_frameBufferCache[frameToDecode].requiredPreviousFrameIndex();
     } while (frameToDecode != notFound && m_frameBufferCache[frameToDecode].status() != ImageFrame::FrameComplete);
 
-    // The |rend| variable is needed by some compilers that can't correctly
-    // select from const and non-const versions of overloaded functions.
-    // Can remove the variable if Android compiler can compile
-    // 'iter != framesToDecode.rend()'.
-    Vector<size_t>::const_reverse_iterator rend = framesToDecode.rend();
-    for (Vector<size_t>::const_reverse_iterator iter = framesToDecode.rbegin(); iter != rend; ++iter) {
-        size_t frameIndex = *iter;
+    for (size_t i = framesToDecode.size(); i > 0; --i) {
+        size_t frameIndex = framesToDecode[i - 1];
         if (!m_reader->decode(frameIndex)) {
             setFailed();
             return;
         }
 
         // We need more data to continue decoding.
         if (m_frameBufferCache[frameIndex].status() != ImageFrame::FrameComplete)
             break;
     }
 
@@ skipping 38 matching lines @@
 
     // Update our status to be partially complete.
     buffer->setStatus(ImageFrame::FramePartial);
 
     // Reset the alpha pixel tracker for this frame.
     m_currentBufferSawAlpha = false;
     return true;
 }
 
 } // namespace WebCore