For Flutter, mark each bounds rect as a draw or not.
saveLayer() is the trickiest part: it doesn't draw, but its paired
restore() does, while a restore() paired with save() doesn't.
Change-Id: I5f0dc61ad5543265c5ea2bf41b236f57915847b9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/273501
Reviewed-by: Emmanuel Garcia <egarciad@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
4c690b442f