Merge r10739 and r10752 into 3.7 branch.

build/common.gypi

 # Copyright 2011 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 243 matching lines @@
             # can cause stack overflow.
             # 'StackReserveSize': '297152',
           },
         },
         'conditions': [
           ['OS=="freebsd" or OS=="openbsd"', {
             'cflags': [ '-I/usr/local/include' ],
           }],
           ['OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
             'cflags': [ '-Wall', '<(werror)', '-W', '-Wno-unused-parameter',
-                        '-Wnon-virtual-dtor' ],
+                        '-Wnon-virtual-dtor', '-Woverloaded-virtual' ],
           }],
         ],
       },
       'Release': {
         'conditions': [
           ['OS=="linux" or OS=="freebsd" or OS=="openbsd"', {
             'cflags!': [
               '-O2',
               '-Os',
             ],
@@ skipping 59 matching lines @@
                 # some test cases can cause stack overflow.
                 # 'StackReserveSize': '297152',
               },
             },
           }],
         ],
       },
     },
   },
 }