Hardwire opList lookAhead & lookBack parameters

If/when we double check these settings we can either re-add these parameters or change the code manually.
The driving goal here is to shrink GrRenderTargetOpList.

Change-Id: I7819de18f97e8282e8754e3438130f797ebb3c37
Reviewed-on: https://skia-review.googlesource.com/14381
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
8 files changed