Use the upstream version of libwebp, v0.4.3.

DEPS:
Update to pull v0.4.3 of libwebp from upstream

gyp/libwebp.gyp:
Add new files, as referenced by the gyp file used by Chromium.

resource/tests:
Add regression tests for particular images.

BUG=skia:3442
BUG=skia:3315
BUG=skia:3429

Committed: https://skia.googlesource.com/skia/+/3aa0fb4d80c76b559ff4b82d5e569993aea06da1

Review URL: https://codereview.chromium.org/1178013008
8 files changed