work on raster device clipping

With the flag (SkDevice.h) enabled, I get correct drawing w/ the rasterbackend.

After this lands, hopefully we can work in parallel on gpu/pdf/svg/xps/etc.

BUG=skia:6214

Change-Id: Ie35fee818470aab57aebacca8a2a5b812a552ee2
Reviewed-on: https://skia-review.googlesource.com/8192
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Robert Phillips <robertphillips@google.com>
7 files changed