v8: don't show performance warnings when compiling with msvc

Patch sent upstream: http://codereview.chromium.org/10829109/

deps/v8/tools/gyp/v8.gyp

@@ -721,6 +721,9 @@
                 '../../src/win32-math.h',
               ],
               'msvs_disabled_warnings': [4351, 4355, 4800],
+              'direct_dependent_settings': {
+                'msvs_disabled_warnings': [4351, 4355, 4800],
+              },
               'link_settings':  {
                 'libraries': [ '-lwinmm.lib', '-lws2_32.lib' ],
               },