Use default SkCanvas::saveLayer() flags.

SaveFlags are getting deprecated in Skia, and this CL removes their
saveLayer-related clients.

Also removing an unneeded clip() call - saveLayer() handles it
internally by default these days. Due to this change, a handful of SVG
tests require minor rebaselining.

R=reed@google.com,senorblanco@chromium.org,schenney@chromium.org

Review URL: https://codereview.chromium.org/214023002

git-svn-id: svn://svn.chromium.org/blink/trunk@170119 bbb929c8-8fbe-4397-9dbb-9b2b20218538