Make webkit_gpu build on Win64

webkit/gpu/webkit_gpu.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'conditions': [
       ['inside_chromium_build==0', {
         'webkit_src_dir': '../../../../..',
       },{
@@ skipping 33 matching lines @@
       'conditions': [
         ['inside_chromium_build==0', {
           'dependencies': [
             '<(DEPTH)/webkit/support/setup_third_party.gyp:third_party_headers',
           ],
         }],
       ],
       'defines': [
         'WEBKIT_GPU_IMPLEMENTATION',
       ],
+      # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
+      'msvs_disabled_warnings': [ 4267, ],
     },
   ],
 }