Bug 1078109 - Make sure we initialize tiled textures to the format we're going to upload with. r=jgilbert

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extra : rebase_source : a779c602a9ef55f8a36e0e5886302f3d3d9624f0
Bug 1077842 - Simplify invalid regions for tiled painted layers to avoid complex region operations. r=jrmuizel

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extra : rebase_source : 13cbe5d47b5c79e576627a67b2a6b61b217f9acf