Bug 1041372 - [User Story] Rocketbar behavior for fullscreen apps with navigation chrome

https://bugzilla.mozilla.org/show_bug.cgi?id=1041372
nit: I wonder if you don't want to move the: |chromeBar.style.transform = ....| out of the if/else block since you do the same for both cases.

I know titleBar.style.transform differs and in one case it is based the chromeBar transform but I don't think it worth keeping chromeBar.transform assignment inside the blocks because of that.