Bug 921753 - Part 1: Avoid #including nsStyleStructInlines.h in nsIFrame.h; r=roc

This patch reduces the number of files that transitively #include
gfx/2d.h from 1782 to 1582.
Bug 921753 - Part 2: Move GraphicsFilters outside of gfxPattern.h so that we won't need to #include that header everywhere GraphicsFilter is needed; r=roc