Revert "Fix bug in GrClearOp combining and remove some asserts"

This reverts commit 35f1b20840c61d70ca8e4d49c59bf6b46c1d6152.

Reason for revert: ANGLE failures

Original change's description:
> Fix bug in GrClearOp combining and remove some asserts
>
> The buffer combining code path was combining the ops but never
> telling the external system that the second op could be removed.
>
> Bug: skia:10963
> Change-Id: If015d877ffbbb75964aae9ca92ea760d7041372a
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/339203
> Commit-Queue: Robert Phillips <robertphillips@google.com>
> Reviewed-by: Michael Ludwig <michaelludwig@google.com>

TBR=robertphillips@google.com,michaelludwig@google.com

Change-Id: Ie188190e7ecf2c39ec067296af20a9794636a226
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:10963
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/340177
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
3 files changed