Bug 1021085 - Refactor code to ensure we use the same scrolling ancestor layer everywhere. r=Cwiiis
Bug 1021085 - Fix up the transform used for the compositor side composition bounds. r=Cwiiis
Bug 1021085 - Inflate the painted rect a bit to deal with rounding error. r=Cwiiis
Bug 1021085 - Remove unnecessary transform stored on the paint data. r=Cwiiis
Bug 1021085 - Fix up the Fennec code path as well. r=Cwiiis
Bug 1021085 - Use the entire compositor-side composition bounds as the coherent update rect on B2G. r=Cwiiis r=BenWa
Bug 1021085 - Miscellaneous cleanup. r=Cwiiis