Revert "Implement approx-match support in image filter saveLayer() offscreen."

This reverts commit b97dafefe63ea0a1bbce8e8b209f4920983fb8b9.

SkLightingImageFilter boundaries are incorrect (see GM:lighting).

BUG=skia:
TBR=

Review URL: https://codereview.chromium.org/1048583002
4 files changed