[build] Use MSVS 2015 by default.

gypfiles/standalone.gypi

 # 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 785 matching lines @@
           '_CRT_SECURE_NO_DEPRECATE',
           '_CRT_NONSTDC_NO_DEPRECATE',
           '_USING_V110_SDK71_',
         ],
         'conditions': [
           ['component=="static_library"', {
             'defines': [
               '_HAS_EXCEPTIONS=0',
             ],
           }],
+          ['component=="shared_library"', {
+            'msvs_disabled_warnings': [
+              4251,  # class 'std::xx' needs to have dll-interface.
+            ],
+          }],
         ],
         'msvs_cygwin_dirs': ['<(DEPTH)/third_party/cygwin'],
         'msvs_disabled_warnings': [
           # C4091: 'typedef ': ignored on left of 'X' when no variable is
           #                    declared.
           # This happens in a number of Windows headers. Dumb.
           4091,
 
           # C4127: conditional expression is constant
           # This warning can in theory catch dead code and other problems, but
@@ skipping 635 matching lines @@
               '-fsanitize=cfi-vcall',
               '-fsanitize=cfi-derived-cast',
               '-fsanitize=cfi-unrelated-cast',
             ],
           }],
         ],
       },
     }],
   ],
 }