Turn on optimized debug builds for V8.

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1087 matching lines @@
     'sas_dll_exists': '<!(python <(DEPTH)/build/dir_exists.py <(sas_dll_path))',
     'wix_exists': '<!(python <(DEPTH)/build/dir_exists.py <(wix_path))',
 
     'windows_sdk_default_path': '<(DEPTH)/third_party/platformsdk_win8/files',
     'directx_sdk_default_path': '<(DEPTH)/third_party/directxsdk/files',
 
     # Whether we are using the rlz library or not.  Platforms like Android send
     # rlz codes for searches but do not use the library.
     'enable_rlz%': 0,
 
+    # Turns on compiler optimizations in V8 in Debug build.
+    'v8_optimized_debug%': 1,
+
     'conditions': [
       # The version of GCC in use, set later in platforms that use GCC and have
       # not explicitly chosen to build with clang. Currently, this means all
       # platforms except Windows, Mac and iOS.
       # TODO(glider): set clang to 1 earlier for ASan and TSan builds so that
       # it takes effect here.
       ['os_posix==1 and OS!="mac" and OS!="ios" and clang==0 and asan==0 and lsan==0 and tsan==0 and msan==0', {
         'gcc_version%': '<!(python <(DEPTH)/build/compiler_version.py)',
       }, {
         'gcc_version%': 0,
@@ skipping 3518 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }