bug 925970

* Get rid of slight shift from placeholder e.me elements and actual when in use.
* Specify font-family to use, this is unfortunately a must as we do not map our light font versions to CSS standard names.
* Degrade to older known fonts to support devices from partners that use incorrect fonts (and there are many).

r=peterla
Merge pull request #13270 from nullaus/awesome-bar-ui

bug 925970