Tesellating path renderer: typecast cleanup; logging build fix.

Use SkPoint* for all vertex data. (It was void* to support two different
vertex data formats, which we no longer need.)
Assert that vertex stride == sizeof(SkPoint).
Fix build when LOGGING_ENABLED=1.

BUG=skia:

Review URL: https://codereview.chromium.org/1128083004
1 file changed