Remove Firefox 27 only workaround.

Up min supported version to fixed Firefox version.
Delay importing the actual sync service.

This should prevent conflicts with the master password dialog
showing up during browser startup.

(Hopefully) fixes #1852.
whitespace
missing semicolon
Inject into about:blank regardless of search/hash URL parts.

Refs #1820
Add `responseType` GM_xmlhttpRequest option.

Fixes #1834
Support .responseXML in GM_xmlhttpRequest().
Do not memoize all URI objects to the same key.

Fixes #1874
Correctly set auto_vacuum pragma for script storage databases.

Fixes #1879.
GM_addStyle now returns the added element