Add -Wno-invalid-offsetof to Mac and iOS builds too.

gyp/common_conditions.gypi

 # conditions used in both common.gypi and skia.gyp in chromium
 #
 {
   'defines': [
     'SK_ALLOW_STATIC_GLOBAL_INITIALIZERS=<(skia_static_initializers)',
     'SK_SUPPORT_GPU=<(skia_gpu)',
     'SK_SUPPORT_OPENCL=<(skia_opencl)',
     'SK_FORCE_DISTANCEFIELD_FONTS=<(skia_force_distancefield_fonts)',
   ],
   'conditions' : [
@@ skipping 491 matching lines @@
             }, {
               'MACOSX_DEPLOYMENT_TARGET': '<(skia_osx_deployment_target)',
             }],
           ],
           'GCC_ENABLE_SUPPLEMENTAL_SSE3_INSTRUCTIONS': 'YES',  # -mssse3
           'GCC_SYMBOLS_PRIVATE_EXTERN':                'NO',   # -fvisibility=hidden
           'GCC_INLINES_ARE_PRIVATE_EXTERN':            'NO',   # -fvisibility-inlines-hidden
           'WARNING_CFLAGS': [
             '-Wall',
             '-Wextra',
+            '-Wno-invalid-offsetof',

[tfarina, 2014/10/07 20:05:53]

looks fine, below too.

             '-Wno-unused-parameter',
             '-Wno-uninitialized',  # Disabled because we think GCC 4.2 is bad at this.
           ],
         },
       },
     ],
 
     [ 'skia_os == "ios"',
       {
         'defines': [
@@ skipping 22 matching lines @@
           },
         },
         'xcode_settings': {
           'ARCHS': ['armv7'],
           'CODE_SIGNING_REQUIRED': 'NO',
           'CODE_SIGN_IDENTITY[sdk=iphoneos*]': '',
           'IPHONEOS_DEPLOYMENT_TARGET': '<(ios_sdk_version)',
           'SDKROOT': 'iphoneos',
           'TARGETED_DEVICE_FAMILY': '1,2',
           'OTHER_CPLUSPLUSFLAGS': [
+            '-Wno-invalid-offsetof',
             '-fvisibility=hidden',
             '-fvisibility-inlines-hidden',
           ],
           'GCC_THUMB_SUPPORT': 'NO',
         },
       },
     ],
 
     [ 'skia_os == "android"',
       {
@@ skipping 65 matching lines @@
     [ 'skia_is_bot', {
       'defines': [ 'SK_CRASH_HANDLER' ],
     }],
 
   ], # end 'conditions'
   # The Xcode SYMROOT must be at the root. See build/common.gypi in chromium for more details
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }