ResourceUsageOverlay currently uses (deprecated!) CGContext API directly to draw itself. That's pretty lame. It would be better to draw using WebCore primitives like GraphicsContext and FontCascade.
Created attachment 264696 [details] Patch
Comment on attachment 264696 [details] Patch Clearing flags on attachment: 264696 Committed r191963: <http://trac.webkit.org/changeset/191963>
All reviewed patches have been landed. Closing bug.