Enable 'treating warnings as errors' for 64 bit Win builds

build_gyp/standalone.gypi

 # Copyright 2014 PDFium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Definitions to be used when building stand-alone PDFium binaries.
 
 {
   'variables': {
     'component%': 'static_library',
     'clang%': 0,
@@ skipping 282 matching lines @@
       # Do not add PDFium specific entries here. Add them to the top.
       # ####
     ],
     'msvs_settings': {
       'VCCLCompilerTool': {
         'MinimalRebuild': 'false',
         'BufferSecurityCheck': 'true',
         'EnableFunctionLevelLinking': 'true',
         'RuntimeTypeInfo': 'false',
         'WarningLevel': '3',
+        'WarnAsError': 'true',
         'DebugInformationFormat': '3',
         'Detect64BitPortabilityProblems': 'false',
         'conditions': [
           [ 'msvs_multi_core_compile', {
             'AdditionalOptions': ['/MP'],
           }],
           ['component=="shared_library"', {
             'ExceptionHandling': '1',  # /EHsc
           }, {
             'ExceptionHandling': '0',
           }],
-          ['target_arch=="x64"', {
-            # 64-bit warnings need to be resolved.
-            # https://code.google.com/p/pdfium/issues/detail?id=101
-            'WarnAsError': 'false',
-          }, {
-            'WarnAsError': 'true',
-          }],
           ['clang==1', {
             'AdditionalOptions': [
               # Don't warn about unused function parameters.
               # (This is also used on other platforms.)
               '-Wno-unused-parameter',
               # Don't warn about the "struct foo f = {0};" initialization
               # pattern.
               '-Wno-missing-field-initializers',
 
               # Many files use intrinsics without including this header.
@@ skipping 166 matching lines @@
       ],
     }],  # OS=="win"
     ["use_goma==1", {
       'make_global_settings': [
         ['CC_wrapper', '<(gomadir)/gomacc'],
         ['CXX_wrapper', '<(gomadir)/gomacc'],
       ],
     }],  # use_goma==1
   ],
 }