Reland change to enable deferred image decoding for animated GIFs

TBR=gavinp@chromium.org

BUG=169377,259786,259783

Review URL: https://codereview.chromium.org/19838002

git-svn-id: svn://svn.chromium.org/blink/trunk@154587 bbb929c8-8fbe-4397-9dbb-9b2b20218538