Remove createPath* from GrGpu and GrContext

Now that we have the GrPathRendering class, it doesn't make sense to
have a bunch of shims on on GrGpu. This updates the path rendering
clients to make calls directly on the GrPathRendering object.

BUG=skia:2939
R=bsalomon@google.com

Author: cdalton@nvidia.com

Review URL: https://codereview.chromium.org/578563002
7 files changed