add comment to webkit_appcache.gypi for workaround to bug 105299.

webkit/appcache/webkit_appcache.gypi

 # Copyright (c) 2011 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 76 matching lines @@
          }, {
           'type': '<(component)',
          }],
         ['inside_chromium_build==0', {
           'dependencies': [
             '<(DEPTH)/webkit/support/setup_third_party.gyp:third_party_headers',
           ],
         }],
         [# TODO(dpranke): Figure out why this doesn't work outside of
          # a webkit build - this seems to be a bug in the make gyp generator.
+         # See http://code.google.com/p/chromium/issues/detail?id=105299 .
          'OS!="mac" and inside_chromium_build==1', {
           'dependencies': [
             '<(webkit_src_dir)/Source/WebKit/chromium/WebKit.gyp:webkit',
           ],
         }],
       ],
     },
   ],
 }