Replace GrQuadList with variable-length quad buffer

Change-Id: I5cc391e8d143032893511695961f5251f40e8291
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/223803
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
9 files changed