GIF: Use SkTArray instead of std::vector

Speculative fix for a memory regression seen in Chromium. Chromium
previously used a WTF::Vector, which has a growth factor of 1.5, as does
SkTArray. Depending on the implementation of std::vector, this may slow
the allocation of memory.

Bug: 758946
Change-Id: I323390027467e32a6c66667c927fae0aba292446
Reviewed-on: https://skia-review.googlesource.com/40777
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
2 files changed