Build in C++11 mode on Macs.

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_DISTANCE_FIELD_TEXT=<(skia_force_distance_field_text)',
   ],
   'conditions' : [
@@ skipping 512 matching lines @@
           'conditions': [
             [ 'skia_warnings_as_errors', { 'GCC_TREAT_WARNINGS_AS_ERRORS': 'YES' }],
             [ 'skia_arch_width == 32', { 'ARCHS': ['i386']   }],
             [ 'skia_arch_width == 64', { 'ARCHS': ['x86_64'] }],
             [ 'skia_osx_deployment_target==""', {
               'MACOSX_DEPLOYMENT_TARGET': '10.6', # -mmacos-version-min, passed in env to ld.
             }, {
               'MACOSX_DEPLOYMENT_TARGET': '<(skia_osx_deployment_target)',
             }],
           ],
+          'CLANG_CXX_LANGUAGE_STANDARD':               'c++11',
           'GCC_ENABLE_SUPPLEMENTAL_SSE3_INSTRUCTIONS': 'YES',  # -mssse3
           'GCC_SYMBOLS_PRIVATE_EXTERN':                'NO',   # -fvisibility=hidden
           'GCC_INLINES_ARE_PRIVATE_EXTERN':            'NO',   # -fvisibility-inlines-hidden
           'GCC_CW_ASM_SYNTAX':                         'NO',   # remove -fasm-blocks
           'GCC_ENABLE_PASCAL_STRINGS':                 'NO',   # remove -mpascal-strings
           'GCC_WARN_ABOUT_INVALID_OFFSETOF_MACRO':     'NO',   # -Wno-invalid-offsetof
           'WARNING_CFLAGS': [
             '-Wall',
             '-Wextra',
             '-Winit-self',
@@ skipping 112 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',
   },
 }