Bug 927254 - Purge SkiaGL texture cache on memory pressure r=gwright

--HG--
extra : rebase_source : 0b6c68c129319c96ad3056ab7b6321c04c7fbcb5
Bug 932180 - Rewrite decompiler's bytecode parser to not need SRC_HIDDEN annotations. r=jandem
Bug 933030 - Eliminate thebes use in CanvasRenderingContext2D.cpp. r=roc