Enable MSVC warning C4018 for various directories that seem to pass as-is.

net/third_party/nss/ssl.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'targets': [
     {
       'target_name': 'libssl',
       'type': '<(component)',
       'product_name': 'crssl',  # Don't conflict with OpenSSL's libssl
@@ skipping 44 matching lines @@
       ],
       'sources!': [
         'ssl/os2_err.c',
         'ssl/os2_err.h',
       ],
       'defines': [
         'NO_PKCS11_BYPASS',
         'NSS_ENABLE_ECC',
         'USE_UTIL_DIRECTLY',
       ],
-      'msvs_disabled_warnings': [4018, 4244, 4267],
+      'msvs_disabled_warnings': [4244, 4267],
       'variables': {
         'clang_warning_flags_unset': [
           # ssl uses PR_ASSERT(!"foo") instead of PR_ASSERT(false && "foo")
           '-Wstring-conversion',
         ],
       },
       'conditions': [
         ['component == "shared_library"', {
           'conditions': [
             ['OS == "mac" or OS == "ios"', {
@@ skipping 100 matching lines @@
       'configurations': {
         'Debug_Base': {
           'defines': [
             'DEBUG',
           ],
         },
       },
     },
   ],
 }