b7d209a448
According to the GIF spec (http://www.w3.org/Graphics/GIF/spec-gif89a.txt), this block is optional, and its scope is only the first graphic rendering block that follows. The spec doesn't mention what default values of frame dimensions, offsets, duration and transparent index to use in such a case, though. So, we use the defaults used by GIF reader in Chromium: https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageReader.h&l=186 (cherry picked from commit d51f3e40698284ffc4831e7d8de7ae59d453f41d) Change-Id: Iecc6967847192483770e85ac15fe2835cd01ce7b