Force inclusion of build/common.gypi for all chromium gyp files.

tools/imagediff/image_diff.gyp

 # Copyright (c) 2009 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.
 
 {
-  'includes': [
-    '../../build/common.gypi',
-  ],
   'targets' : [ 
     {
       'target_name': 'image_diff',
       'type': 'executable',
       'msvs_guid': '50B079C7-CD01-42D3-B8C4-9F8D9322E822',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../base/base.gyp:base_gfx',
       ],
       'sources': [
         'image_diff.cc',
       ],
     },
   ],
 }