Store the texture image information in a std::vector instead of a std::map. BUG=angle:909 Change-Id: Ib595306f6cf0633b16bff6389373c2bb2cc29ec9 Reviewed-on: https://chromium-review.googlesource.com/248051 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Nicolas Capens <capn@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>