Size buffers properly for bulk interface between Painter and SkDraw

This brings drawing performance back into parity.

Change-Id: I57af4dbf027786773bd60045bb42b2e1365e12d5
Reviewed-on: https://skia-review.googlesource.com/c/166741
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Herb Derby <herb@google.com>
Auto-Submit: Herb Derby <herb@google.com>
1 file changed