py, firefox: use right port when testing if extension can be connected to.

I didn't find Python unit testing support in crazy-fun-build, is there?

Author: sevaseva

Diff for: py/selenium/webdriver/firefox/extension_connection.py

@@ -72,7 +72,7 @@ def connect_and_quit(self):
     @classmethod
     def is_connectable(self):
         """Trys to connect to the extension but do not retrieve context."""
-        utils.is_connectable(self.port)
+        utils.is_connectable(self.profile.port)
 
 class ExtensionConnectionError(Exception):
     """An internal error occurred int the extension.