ccpr: Remove the dangling pointer from GrCCDrawPathsOp

Actually takes a ref on fOwningPerOpListPaths, instead of just
asserting it continues to exist. Removes unnecessary asserts
surrounding dangling pointers.

Bug: skia:8359
Change-Id: Ie80da55510f320452bd9ee3a4b38bd59d48681a0
Reviewed-on: https://skia-review.googlesource.com/154684
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
7 files changed