Convert GrRenderTargetOpList::tryConcat to an OOP-style method

This method is going to become more complicated once we account for
non-overlap constraints. This change helps keep the argument list size
and complexity under wraps.

Bug: skia:8671
Change-Id: I34ef858e196040f194f080540f5fc190964fb6f0
Reviewed-on: https://skia-review.googlesource.com/c/185360
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
2 files changed