Make SkLiteDL::draw() const.

Nothing interesting here.  Just slapping const all over the place.

BUG=skia:6484

Change-Id: I639001754aca6d129c40e9acddc9b2d3730fed0c
Reviewed-on: https://skia-review.googlesource.com/13184
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
2 files changed