DBC: Adds simdbc64 target, adds arm64 arithmetic overflow logic

tools/gyp/configurations_xcode.gypi

 # 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.
 
 # READ BEFORE EDITING:
 # Do not add Dart VM specific configuration to this file. Instead,
@@ skipping 62 matching lines @@
       },
       'Dart_Macos_simarm64_Base': {
         'abstract': 1,
       },
       'Dart_Macos_simmips_Base': {
         'abstract': 1,
       },
       'Dart_Macos_simdbc_Base': {
         'abstract': 1,
       },
+      'Dart_Macos_simdbc64_Base': {
+        'abstract': 1,
+      },
       'Dart_Macos_Debug': {
         'abstract': 1,
         'xcode_settings': {
           'OTHER_CFLAGS': [
             '-fno-omit-frame-pointer',
             '-mno-omit-leaf-frame-pointer',
           ],
         },
       },
       'Dart_Macos_Release': {
@@ skipping 10 matching lines @@
         'xcode_settings': {
           'OTHER_CFLAGS': [
             '-fomit-frame-pointer',
             '-momit-leaf-frame-pointer',
           ],
         },
       },
     },
   },
 }