Bug 1065008 - Consider the shadow transform when computing the opaque rect to use for culling. r=roc

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extra : rebase_source : 2b162f272016193e2af3316c9f18d37125050863
Bug 1065008 - Reftest for compositor culling bug. r=roc

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extra : rebase_source : 77c5343a91dc05b6d0a4dac99503331f4cfdb3e7