Add tab.IsServiceWorkerReadyOrNotRegist() which tells whether serviceworker registration is finished

catapult_build/js_checks.py

 # Copyright (c) 2014 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 re
 
 import eslint
 from py_vulcanize import strip_js_comments
 
 from catapult_build import parse_html
@@ skipping 80 matching lines @@
   soup = parse_html.BeautifulSoup(contents)
   script_elements = soup.find_all('script', src=None)
   return [_FirstStatement(e.get_text()) for e in script_elements]
 
 
 def _FirstStatement(contents):
   """Extracts the first statement in some JS source code."""
   stripped_contents = strip_js_comments.StripJSComments(contents).strip()
   matches = re.match('^(.*?);', stripped_contents, re.DOTALL)
   if not matches:
-    return ''
+    return contents
   return matches.group(1).strip()
 
 
 def RunChecks(input_api, output_api, excluded_paths=None):
 
   def ShouldCheck(affected_file):
     if not excluded_paths:
       return True
     path = affected_file.LocalPath()
     return not any(re.match(pattern, path) for pattern in excluded_paths)
 
   return JSChecker(input_api, output_api, file_filter=ShouldCheck).RunChecks()