Make assertion scopes thread safe.

tools/gyp/v8.gyp

 # Copyright 2012 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 194 matching lines @@
         '../../src/accessors.h',
         '../../src/allocation.cc',
         '../../src/allocation.h',
         '../../src/api.cc',
         '../../src/api.h',
         '../../src/apiutils.h',
         '../../src/arguments.cc',
         '../../src/arguments.h',
         '../../src/assembler.cc',
         '../../src/assembler.h',
+        '../../src/assert-scope.h',
         '../../src/ast.cc',
         '../../src/ast.h',
         '../../src/atomicops.h',
         '../../src/atomicops_internals_x86_gcc.cc',
         '../../src/bignum-dtoa.cc',
         '../../src/bignum-dtoa.h',
         '../../src/bignum.cc',
         '../../src/bignum.h',
         '../../src/bootstrapper.cc',
         '../../src/bootstrapper.h',
@@ skipping 697 matching lines @@
         }],
         ['v8_compress_startup_data=="bz2"', {
           'libraries': [
             '-lbz2',
           ]
         }],
       ],
     },
   ],
 }