Add TestGypXcodeNinja to run tests against the xcode-ninja generator

test/mac/gyptest-app-error.py

Index: test/mac/gyptest-app-error.py
diff --git a/test/mac/gyptest-app-error.py b/test/mac/gyptest-app-error.py
index a62af6b852a815cb325caf430030cb8d10407aa1..8f3cef28c11d154979183e5ef29d2e92d93e0c9f 100755
--- a/test/mac/gyptest-app-error.py
+++ b/test/mac/gyptest-app-error.py
@@ -34,7 +34,8 @@ if sys.platform == 'darwin':
   test.build('test-error.gyp', test.ALL, chdir='app-bundle')
 
   # Ninja pipes stderr of subprocesses to stdout.
-  if test.format == 'ninja' and expected_error in test.stdout():
+  if test.format in ['ninja', 'xcode-ninja'] \
+      and expected_error in test.stdout():
     saw_expected_error[0] = True
 
   if saw_expected_error[0]: