Revert "Revert "Allow GrDrawOpAtlas to grow as needed""

Bug: skia:3550
Change-Id: I11a3b39ed7470542447f0e46141a26eef7a9bdaf
Reviewed-on: https://skia-review.googlesource.com/47240
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
12 files changed