Run Mojo apptests step on Windows main and cq bots.

testing/scripts/mojo_apptests.py

 #!/usr/bin/env python
 # Copyright 2015 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.
 
 import json
 import os
 import sys
 
 
 import common
 
 
 def main_run(args):
   runner = os.path.join(common.SRC_DIR, 'mojo', 'tools', 'apptest_runner.py')
   build_dir = os.path.join(common.SRC_DIR, 'out', args.build_config_fs)
 
   with common.temporary_file() as tempfile_path:
-    rc = common.run_command([runner, build_dir, '--verbose',
+    rc = common.run_command([sys.executable, runner, build_dir, '--verbose',
                              '--write-full-results-to', tempfile_path])
     with open(tempfile_path) as f:
       results = json.load(f)
 
   parsed_results = common.parse_common_test_results(results, test_separator='.')
   failures = parsed_results['unexpected_failures']
 
   json.dump({
       'valid': bool(rc <= common.MAX_FAILURES_EXIT_STATUS and
                    ((rc == 0) or failures)),
       'failures': failures.keys(),
   }, args.output)
 
   return rc
 
 
 def main_compile_targets(args):
   json.dump(['mandoline:tests'], args.output)
 
 
 if __name__ == '__main__':
   funcs = {
     'run': main_run,
     'compile_targets': main_compile_targets,
   }
   sys.exit(common.run_script(sys.argv[1:], funcs))