Bug 859257 - Backout original fix 4c0d13ce4c4a since ab6e995676bd has superseded it
Bug 855763 - [Responsive Mode] Fix for intermittent browser_responsiveuiaddcustompreset.js | Test timed out, | Found a tab after previous test timed out: data:text/html,foo, browser_Services.js | Services.prompt is an nsIPromptService; r=jwalker