Put a copy of the wpt upstreaming scripts in-tree.

This is copied from gecko, which is slightly unfortunate. However it allows
committing changes to wpt directly in-tree and having them upstreamed in the
next update.

tests/wpt/update/__init__.py

@@ -0,0 +1,38 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#!/usr/bin/env python
+import os
+import subprocess
+import sys
+
+from mozlog.structured import structuredlog
+
+here = os.path.split(__file__)[0]
+
+sys.path.insert(0, os.path.abspath(os.path.join(here, os.pardir, "harness")))
+sys.path.insert(0, os.path.abspath(os.path.join(here, os.pardir, "tests", "tools", "scripts")))
+
+from wptrunner.update import setup_logging, WPTUpdate
+from wptrunner.update.base import exit_unclean
+
+from . import updatecommandline
+from .update import UpdateRunner
+
+def run_update(logger, **kwargs):
+    updater = WPTUpdate(logger, runner_cls=UpdateRunner, **kwargs)
+    return updater.run()
+
+
+if __name__ == "__main__":
+    args = updatecommandline.parse_args()
+    logger = setup_logging(args, {"mach": sys.stdout})
+    assert structuredlog.get_default_logger() is not None
+
+
+    rv = run_update(logger, **args)
+    if rv is exit_unclean:
+        sys.exit(1)
+    else:
+        sys.exit(0)