Second part of piecemeal revert

This is a partial revert of https://codereview.chromium.org/2514543002 (Defer more renderTargetContexts in the GPU image filter paths - take 2)

I have been unable to reproduce the performance regression in crbug.com/668179 locally so intend to revert the above CL piecemeal.

BUG=668179

Change-Id: Iee9d0164f85ae33ff8dfa9b3eb01c07fd825f017
Reviewed-on: https://skia-review.googlesource.com/5541
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>