Remove GraphicsContext's deferred save mechanism.

The new Skia recording backend is not as sensitive to the number of draw
ops as the old one -> we don't have to bend over backwards to suppress
unneeded saves at the GC level.

While this results in a slight increase in the number of recorded ops,
the unnecessary saves and restores are optimized out by the bounding box
hierarchy - so there is no playback/rasterization time penalty (Skia
also has an explicit save/restore optimizer which can be used for this
purpose if we ever decide to drop the BBH).

Local perf measurements show no rasterization impact and a minor (<1%)
improvement for record time.

R=schenney@chromium.org,senorblanco@chromium.org

Review URL: https://codereview.chromium.org/653153004

git-svn-id: svn://svn.chromium.org/blink/trunk@183750 bbb929c8-8fbe-4397-9dbb-9b2b20218538