Bug 942033 - Build security/manager in unified mode; r=bsmith

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extra : rebase_source : d48b78001772e0421a6dfc2ecd204434c33cd2d4
Bug 907743 - Align display port to tile boundaries when tiles are enabled. r=botond,kats

This aligns display ports to tile boundaries, taking care to compensate for
the difference between the requested scroll position and the actual scroll
position.