Bug 867474 - Split BasicShadowableLayerManager into a separate ClientLayerManager. r=nrc

--HG--
rename : gfx/layers/basic/BasicCanvasLayer.cpp => gfx/layers/CopyableCanvasLayer.cpp
rename : gfx/layers/basic/BasicCanvasLayer.h => gfx/layers/CopyableCanvasLayer.h
rename : gfx/layers/basic/BasicCanvasLayer.cpp => gfx/layers/client/ClientCanvasLayer.cpp
rename : gfx/layers/basic/BasicCanvasLayer.h => gfx/layers/client/ClientCanvasLayer.h
rename : gfx/layers/basic/BasicColorLayer.cpp => gfx/layers/client/ClientColorLayer.cpp
rename : gfx/layers/basic/BasicContainerLayer.cpp => gfx/layers/client/ClientContainerLayer.cpp
rename : gfx/layers/basic/BasicContainerLayer.h => gfx/layers/client/ClientContainerLayer.h
rename : gfx/layers/basic/BasicImageLayer.cpp => gfx/layers/client/ClientImageLayer.cpp
rename : gfx/layers/basic/BasicLayerManager.cpp => gfx/layers/client/ClientLayerManager.cpp
rename : gfx/layers/basic/BasicLayers.h => gfx/layers/client/ClientLayerManager.h
rename : gfx/layers/basic/BasicThebesLayer.cpp => gfx/layers/client/ClientThebesLayer.cpp
rename : gfx/layers/basic/BasicThebesLayer.h => gfx/layers/client/ClientThebesLayer.h
rename : gfx/layers/basic/BasicTiledThebesLayer.cpp => gfx/layers/client/ClientTiledThebesLayer.cpp
rename : gfx/layers/basic/BasicTiledThebesLayer.h => gfx/layers/client/ClientTiledThebesLayer.h
Bug 864287 - Add back code to readback IOSurface plugins when using BasicLayers. r=BenWa