Simplify GrClip::getConservativeBounds() signature

It turns out no one was using the intersection of rect functionality on
GrClip, and this helps simplify what the new clip stack needs to define.

Bug: skia:10205
Change-Id: If85a0c744dd68a8ad2f380b54a539ac74850e4ac
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/289440
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
17 files changed