Move webkit/gpu into webkit/common/gpu

webkit/common/gpu/webkit_gpu.gyp

 # Copyright (c) 2013 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.
 
 {
   'conditions': [
     # TODO(stuartmorgan): All dependencies from code built on iOS to
     # webkit/ should be removed, at which point this condition can be
     # removed.
     ['OS != "ios"', {
@@ skipping 36 matching lines @@
           'defines': [
             'WEBKIT_GPU_IMPLEMENTATION',
           ],
           # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
           'msvs_disabled_warnings': [ 4267, ],
         },
       ],
     }],
   ],
 }