clang: Let release builds use -O3, like on gcc.

build/common.gypi

 # Copyright (c) 2011 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 626 matching lines @@
       'conditions': [
         ['OS=="win" and component=="shared_library"', {
           # See http://msdn.microsoft.com/en-us/library/aa652367.aspx
           'win_release_RuntimeLibrary%': '2', # 2 = /MT (nondebug DLL)
           'win_debug_RuntimeLibrary%': '3',   # 3 = /MTd (debug DLL)
         }, {
           # See http://msdn.microsoft.com/en-us/library/aa652367.aspx
           'win_release_RuntimeLibrary%': '0', # 0 = /MT (nondebug static)
           'win_debug_RuntimeLibrary%': '1',   # 1 = /MTd (debug static)
         }],
-        ['OS=="mac" and clang==1', {
-          # TODO(thakis): Remove this once http://llvm.org/PR10031 is fixed.
-          'mac_release_optimization%': '2',
-        }],
       ],
     },
     'conditions': [
       ['branding=="Chrome"', {
         'defines': ['GOOGLE_CHROME_BUILD'],
       }, {  # else: branding!="Chrome"
         'defines': ['CHROMIUM_BUILD'],
       }],
       ['toolkit_views==1', {
         'defines': ['TOOLKIT_VIEWS=1'],
@@ skipping 1118 matching lines @@
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }
 
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