[ninja/mac] Add xcode_emulation support for -Wobjc-missing-property-synthesis.

test/ios/gyptest-app-error-ios.py

+#!/usr/bin/env python
+
+# Copyright (c) 2012 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+Verifies that ios app bundles are built correctly.
+"""
+
+import TestGyp
+
+import sys
+
+if sys.platform == 'darwin':
+  expected_error = 'auto property synthesis is synthesizing property not ' \
+      'explicitly synthesized'
+
+  test = TestGyp.TestGyp(formats=['xcode', 'ninja'])
+
+  test.run_gyp('test-error.gyp', chdir='app-bundle')
+
+  test.build('test-error.gyp', test.ALL, chdir='app-bundle')
+
+  if expected_error in test.stdout():
+    test.pass_test()
+  else:
+    test.fail_test()