Remove ability to add waitOp to GrOpsTask.

This isn't used anywhere since we no have GrWaitRenderTask.

Change-Id: I31e5f89fabf547346886edba5db1fac819096146
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/310377
Reviewed-by: Adlai Holler <adlai@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
2 files changed