override SkTypeface::onOpenStream()
override SkTypeface::onOpenStream()

note: getTables APIs are not overridden yet, causing them to take the slow
openstream case each time. We should fix this, since openStream for windows
itself is slow (not native).
Review URL: https://codereview.chromium.org/12941006

csulmone/skia,csulmone/skia,csulmone/skia,csulmone/skia