Unable to add new search engines

[GoogleCodeExporter]

To reproduce:
1. Install organize-search-engines v1.7
2. Visit https://addons.mozilla.org/en-US/firefox/addon/debian-packages/
3. Click "+ Add to Firefox"

Expected: Debian package search gets added 
Actual: nothing happens, except for a message like this in the browser console:

[Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) 
[nsIStringBundle.GetStringFromName]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)" 
 location: "JS frame :: 
chrome://seorganizer/content/searchServiceModifications.js :: confirmAddEngine 
:: line 69"  data: no] searchServiceModifications.js:69

This is on Firefox 29.0, as shipped in Ubuntu 14.04 "trusty".  The issue 
persists even when all other addons are disabled (including the Ubuntu Firefox 
modifications extension v2.8 that bundled with Ubuntu's distribution of 
Firefox).

Original issue reported on code.google.com by [email protected] on 10 Jun 2014 at 5:25