libwebp: cherry-pick lossless decoding fix

third_party/libwebp/dec/vp8l.c

 // Copyright 2012 Google Inc. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the COPYING file in the root of the source
 // tree. An additional intellectual property rights grant can be found
 // in the file PATENTS. All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
 // main entry for the decoder
@@ skipping 882 matching lines @@
         src += length;
       }
       col += length;
       while (col >= width) {
         col -= width;
         ++row;
         if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) {
           process_func(dec, row);
         }
       }
-      if (src < src_last) {
+      if (src < src_end) {
         if (col & mask) htree_group = GetHtreeGroupForPos(hdr, col, row);
         if (color_cache != NULL) {
           while (last_cached < src) {
             VP8LColorCacheInsert(color_cache, *last_cached++);
           }
         }
       }
     } else if (code < color_cache_limit) {  // Color cache
       const int key = code - len_code_limit;
       assert(color_cache != NULL);
@@ skipping 481 matching lines @@
   VP8LClear(dec);
   return 1;
 
  Err:
   VP8LClear(dec);
   assert(dec->status_ != VP8_STATUS_OK);
   return 0;
 }
 
 //------------------------------------------------------------------------------