Make GN build match gyp (/bigobj everywhere) and remove now-unnecessary settings

content/content_shell_and_tests.gyp

 # Copyright 2013 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.
 
 {
   'variables': {
     'chromium_code': 1,  # Use higher warning level.
   },
-  'target_defaults': {
-    'conditions': [
-      # TODO(jschuh): Remove this after crbug.com/173851 gets fixed.
-      ['OS=="win" and target_arch=="x64"', {
-        'msvs_settings': {
-          'VCCLCompilerTool': {
-            'AdditionalOptions': ['/bigobj'],
-          },
-        },
-      }],
-    ],
-  },
   'includes': [
     'content_tests.gypi',
   ],
   'conditions': [
     ['OS != "ios"', {
       'includes': [
         '../build/win_precompile.gypi',
         'content_shell.gypi',
       ],
     }],
   ],
 }