Resolve issue with flush-time opsTask management

Despite what the bug says, I believe the only issue here was that
all the flush-time opsTasks weren't guaranteed to be in
'fOnFlushRenderTasks'. Since the users of flush-time opsTasks
use GrRenderTargetContext::addDrawOp, if the opsTask were to be
split, new ops would be added to the correct/new opsTask.

Bug: skia:9357

Change-Id: I90577bcc852419a9e0c31d858f71cda9f6f6b6a3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/336435
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Adlai Holler <adlai@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
5 files changed