Add contenteditable caret position workaround for Firefox
Add contenteditable caret position workaround for Firefox

This fixes an issue when focusing on an empty contenteditable element,
the caret would shift downwards in Firefox 36.0.1.

Not really the same issue, but see
https://bugzilla.mozilla.org/show_bug.cgi?id=904846.

imiric/tiq-web,imiric/tiq-web