[linux] Use _GLIBCXX_DEBUG in Debug builds by default for better checking.

build/toolchain.gypi

 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 43 matching lines @@
     # on the target.
     'v8_can_use_vfp32dregs%': 'false',
     'arm_test_noprobe%': 'off',
 
     # Similar to vfp but on MIPS.
     'v8_can_use_fpu_instructions%': 'true',
 
     # Similar to the ARM hard float ABI but on MIPS.
     'v8_use_mips_abi_hardfloat%': 'true',
 
+    # Force disable libstdc++ debug mode.
+    'disable_glibcxx_debug%': 0,
+
     'v8_enable_backtrace%': 0,
 
     # Enable profiling support. Only required on Windows.
     'v8_enable_prof%': 0,
 
     # Some versions of GCC 4.5 seem to need -fno-strict-aliasing.
     'v8_no_strict_aliasing%': 0,
 
     # Chrome needs this definition unconditionally. For standalone V8 builds,
     # it's handled in build/standalone.gypi.
@@ skipping 1053 matching lines @@
         ],
         'conditions': [
           ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd" or \
             OS=="qnx" or OS=="aix"', {
             'cflags': [ '-Woverloaded-virtual', '<(wno_array_bounds)', ],
           }],
           ['OS=="linux" and v8_enable_backtrace==1', {
             # Support for backtrace_symbols.
             'ldflags': [ '-rdynamic' ],
           }],
+          ['OS=="linux" and disable_glibcxx_debug==0', {
+            # Enable libstdc++ debugging facilities to help catch problems
+            # early, see http://crbug.com/65151 .
+            'defines': ['_GLIBCXX_DEBUG=1',],
+          }],
           ['OS=="aix"', {
             'ldflags': [ '-Wl,-bbigtoc' ],
           }],
           ['OS=="android"', {
             'variables': {
               'android_full_debug%': 1,
             },
             'conditions': [
               ['android_full_debug==0', {
                 # Disable full debug if we want a faster v8 in a debug build.
@@ skipping 108 matching lines @@
           ['v8_enable_slow_dchecks==1', {
             'defines': [
               'ENABLE_SLOW_DCHECKS',
             ],
           }],
         ],  # conditions
       },  # Release
     },  # configurations
   },  # target_defaults
 }