[inspector] suppress build warnings on windows/clang

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 435 matching lines @@
     # fpxx - compatibility mode, it chooses fp32 or fp64 depending on runtime
     #        detection
     'mips_fpu_mode%': 'fp32',
   },
   'target_defaults': {
     'variables': {
       'v8_code%': '<(v8_code)',
       'clang_warning_flags': [
         # TODO(thakis): https://crbug.com/604888
         '-Wno-undefined-var-template',
+        # TODO(yangguo): issue 5258
+        '-Wno-nonportable-include-path',
       ],
       'conditions':[
         ['OS=="android"', {
           'host_os%': '<(host_os)',
         }],
       ],
     },
     'includes': [ 'set_clang_warning_flags.gypi', ],
     'default_configuration': 'Debug',
     'configurations': {
@@ skipping 1038 matching lines @@
               '-fsanitize=cfi-vcall',
               '-fsanitize=cfi-derived-cast',
               '-fsanitize=cfi-unrelated-cast',
             ],
           }],
         ],
       },
     }],
   ],
 }