Fix decoding gifs with too-big-bounds

Update libgifcodec to include the fix and test an animated gif with
too-big-bounds. This image (alphabetAnim.gif, checked into our skimage
assets to be downloaded and tested on the bots) has bounds that extend
outside the edge of the canvas.
https://skia-review.googlesource.com/c/libgifcodec/+/339831
broke this image, so add it to our visual tests to verify that it's
fixed.

Change-Id: Id21c1858c72822db7c59d84591401ec9f74420f9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/353624
Commit-Queue: Derek Sollenberger <djsollen@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Auto-Submit: Leon Scroggins <scroggo@google.com>
3 files changed