Refactor SkPoint reading for MakeFromBuffer

Now that all the SubRun types have been converted over to use
the bulk point API. The common code can be extracted and shared.

Change-Id: I2a5a515f496291c91a5ae41112f187ee9cec0fd3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/566559
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
1 file changed