Bug 1028460 - part 1, Implement a mozilla::Sides type that represents a set of sides that can be used for the GetSkipSides() result among other things.  r=roc
Bug 1028460 - part 2, Implement a mozilla::LogicalSides type that represents a set of logical sides that can be used for the GetLogicalSkipSides() result among other things.  r=roc
Bug 1028460 - part 3, Change the return type for Get*SkipSides().  r=roc
Bug 1028460 - part 4, Remove LOGICAL_SIDE* and use the LogicalSideBits enum values instead.  r=roc
Bug 1031444 - Add missing COMPUTED_STYLE_PROP declaration for 'box-decoration-break'.  r=roc