Bug 961687: ShrinkingUI not sending URL. Fix mismatched 'transitionend' animation listener callbacks.

Add 2 state vars and updaters to track the last animation callback for the "tip" (slide animation) and "appFrame" (tilt animation). This fixes all the appFrame and tip === null issues (as far as one application reference is concerned) without getting very complex.

UX should be exactly the same otherwise.