Changes to make 2pt gradient source code better aligned with our future doc

See https://skia-review.googlesource.com/c/skia/+/89340 for the doc

Bug: skia:
Change-Id: I7a57eea317bbc424278c9eaa524a6b7e3b36178e
Reviewed-on: https://skia-review.googlesource.com/90203
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>
1 file changed