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+
Backed out changeset 7ecc55933499 for red on OSX
Back out bug 831237 for red on a CLOSED TREE
Bug 883744 - Add pointer null check. r=doublec, a=leo+
Bug 884146 - B2G MMS: Can not receive MMS from Far-stone sim card. r=vyang, a=leo+
Bug 883017 - Send MMS with UTF-8 charset. r=gene.lian, a=leo+

Some MMSC seems to be doing bad things if we don't encode/specify the
correct encoding: SFR and Bouygues Telecom delivers UTF-8 destroyed,
while Free Mobile and Orange did a good job. Setting the charset to
UTF-8 makes those four carriers (and probably a lot more) happy.
Merge b2g18 to v1.1hd. a=merge