Add TestGypXcodeNinja to run tests against the xcode-ninja generator

test/copies/gyptest-slash.py

Index: test/copies/gyptest-slash.py
diff --git a/test/copies/gyptest-slash.py b/test/copies/gyptest-slash.py
index 81a4f42a323d45ac87e5e2d64d94b6a0452265d3..f7d6e0b178515b8b5de415ff49b5e3ce68a7af72 100755
--- a/test/copies/gyptest-slash.py
+++ b/test/copies/gyptest-slash.py
@@ -11,7 +11,10 @@ Verifies file copies with a trailing slash in the destination directory.
 import TestGyp
 
 test = TestGyp.TestGyp()
-test.run_gyp('copies-slash.gyp', chdir='src')
+test.run_gyp('copies-slash.gyp',
+             '-G', 'xcode_ninja_target_pattern=^copies',
+             chdir='src')
+
 test.relocate('src', 'relocate/src')
 test.build('copies-slash.gyp', chdir='relocate/src')