Update V8 to version 3.12.

tools/gyp/configurations_xcode.gypi

-# Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+# Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
+# The purpose of this file and others in this directory is to simulate
+# the Chromium build enviroment. This file is included in all GYP
+# files that are used by the Dart project. This includes V8's GYP
+# files.
+
+# READ BEFORE EDITING:
+# Do not add Dart VM specific configuration to this file. Instead,
+# modify runtime/tools/gyp/runtime-configurations.gypi.
+
 {
-  'variables': {
-    'dart_debug_optimization_level%': '2',
-  },
   'target_defaults': {
     'configurations': {
       'Dart_Base': {
         'xcode_settings': {
           # To switch to the LLVM based backend change the two lines below.
           #'GCC_VERSION': 'com.apple.compilers.llvmgcc42',
           'GCC_VERSION': '4.2',
           'GCC_C_LANGUAGE_STANDARD': 'ansi',
           'GCC_ENABLE_CPP_EXCEPTIONS': 'NO', # -fno-exceptions
           'GCC_ENABLE_CPP_RTTI': 'NO', # -fno-rtti
           'GCC_DEBUGGING_SYMBOLS': 'default', # -g
           'GCC_GENERATE_DEBUGGING_SYMBOLS': 'YES', # Do not strip symbols
           'GCC_SYMBOLS_PRIVATE_EXTERN': 'YES', # -fvisibility=hidden
           'GCC_INLINES_ARE_PRIVATE_EXTERN': 'YES', # -fvisibility-inlines-hidden
           'GCC_WARN_NON_VIRTUAL_DESTRUCTOR': 'YES', # -Wnon-virtual-dtor
-          # TODO(v8-team): Fix V8 build.
-          #'GCC_WARN_HIDDEN_VIRTUAL_FUNCTIONS': 'YES', # -Woverloaded-virtual
           'GCC_TREAT_WARNINGS_AS_ERRORS': 'YES', # -Werror
           'WARNING_CFLAGS': [
             '<@(common_gcc_warning_flags)',
             '-Wtrigraphs', # Disable Xcode default.
             '-Wreturn-type',
             '-Werror=return-type',
           ],
 
           # Generate PIC code as Chrome is switching to this.
           'GCC_DYNAMIC_NO_PIC': 'NO',
 
           # When searching for header files, do not search
           # subdirectories. Without this option, vm/assert.h conflicts
           # with the system header assert.h. Apple also recommend
           # setting this to NO.
           'ALWAYS_SEARCH_USER_PATHS': 'NO',
 
           # Attempt to remove compiler options that Xcode adds by default.
           'GCC_CW_ASM_SYNTAX': 'NO', # Remove -fasm-blocks.
 
           'GCC_ENABLE_PASCAL_STRINGS': 'NO',
           'GCC_ENABLE_TRIGRAPHS': 'NO',
           'PREBINDING': 'NO',
         },
       },
-
-      'Dart_ia32_Base': {
-        'xcode_settings': {
-          'ARCHS': [ 'i386' ],
-        },
-      },
-
-      'Dart_x64_Base': {
-        'xcode_settings': {
-          'ARCHS': [ 'x86_64' ],
-        },
-      },
-
-      'Dart_simarm_Base': {
-        'xcode_settings': {
-          'ARCHS': [ 'i386' ],
-          'GCC_OPTIMIZATION_LEVEL': '3',
-        },
-      },
-
-      'Dart_Debug': {
-        'xcode_settings': {
-          'GCC_OPTIMIZATION_LEVEL': '<(dart_debug_optimization_level)',
-        },
-      },
-
-      'Dart_Release': {
-        'xcode_settings': {
-          'GCC_OPTIMIZATION_LEVEL': '3',
-        },
-      },
     },
   },
 }