Bug 945203. Part 1: Add Layers API to annotate layers with hit-test regions. r=kats

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extra : rebase_source : baa695c0d6104f620a5b45a83e5b230ef584abd9
Bug 945203. Part 2: Fix bogus comment. r=mattwoodrow

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extra : rebase_source : a7ef13ff14808109b003a72a6e55b21014801bc0
Bug 945203. Part 3: Implement nsRegion::Swap. r=jrmuizel

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extra : rebase_source : ee43bf510f8d2bac998d24511327c33362044c79
Bug 945203. Part 4: Add nsDisplayEventRegions and build it when painting. r=mats

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extra : rebase_source : 26b71b6a18681e8fc48c6082c8df6263c1bd3739
Bug 945203. Part 5: Remove anonymous namespace. r=mattwoodrow

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extra : rebase_source : c8a35bed286161a339d4d68d4c0d21fb1c391ab2
Bug 945203. Part 6: Move ThebesLayerData to the top level so it can be referenced elsewhere .r=mattwoodrow

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extra : rebase_source : d0df9b439b454a1c6bef1a8f33f2f96754077ff1
Bug 945203. Part 7: Add ScaleRegionToOutsidePixels. r=mattwoodrow

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extra : rebase_source : 1c54863818607c45d04249e5df407b3fb3af40dd
Bug 945203. Part 8: Add FrameLayerBuilder support for capturing nsDisplayEventRegions data into ThebesLayers. r=mattwoodrow

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extra : rebase_source : e61c1bcfa700ac88523fb34eab7c6afd470d0d68