Bug 831237 - Reduce APZC buffer churn. r=BenWa, a=leo+

Prevents the display port from getting smaller as the visible region
approaches the edges of the scrollable rect.
Bug 880932 - Fixed lack of response to APZC paint requests. r=BenWa, a=leo+

All paint requests get tagged with the current nsPresShellId. TabChild will
always trigger a response so APZC doesn't get left hanging.
Bug 883296 - Return empty object instead of null when decoding zero length data in Octet.decodeMultiple. r=gene, a=leo+
Bug 882496 - Fail gracefully if Persona observer methods called before watch(). r=benadida, a=leo+
Bug 882552 - Change Binder Thread's default priority to 0. r=mwu, r=jlebar, a=leo+