Update straggling ImageSource references

Source/platform/image-decoders/gif/GIFImageReader.cpp

 /* -*- Mode: C; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
  * The contents of this file are subject to the Mozilla Public License Version
  * 1.1 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
  * http://www.mozilla.org/MPL/
  *
  * Software distributed under the License is distributed on an "AS IS" basis,
@@ skipping 58 matching lines @@
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 #include "config.h"
 #include "platform/image-decoders/gif/GIFImageReader.h"
 
 #include <string.h>
-#include "platform/graphics/ImageSource.h"
 
 using blink::GIFImageDecoder;
 
 // GETN(n, s) requests at least 'n' bytes available from 'q', at start of state 's'.
 //
 // Note, the hold will never need to be bigger than 256 bytes to gather up in the hold,
 // as each GIF block (except colormaps) can never be bigger than 256 bytes.
 // Colormaps are directly copied in the resp. global_colormap or dynamically allocated local_colormap.
 // So a fixed buffer in GIFImageReader is good enough.
 // This buffer is only needed to copy left-over data from one GifWrite call to the next
@@ skipping 752 matching lines @@
     rowIter = rowBuffer.begin();
     rowsRemaining = m_frameContext->height();
 
     // Clearing the whole suffix table lets us be more tolerant of bad data.
     for (int i = 0; i < clearCode; ++i) {
         suffix[i] = i;
         suffixLength[i] = 1;
     }
     return true;
 }