Bug 856486 (Part 1) - Avoid asserts triggered by rapid off-main-thread decoding. r=jrmuizel
Bug 856486 (Part 2) - Buffer the last fully-decoded frame for multipart images. r=jrmuizel
Bug 856486 (Followup) - Make sure we use the buffered frame, when appropriate, for all callers of GetDrawableImgFrame. r=me
Bug 856486 (Followup 2) - Make sure we use the buffered frame, when appropriate, for all callers of GetDrawableImgFrame. r=me
Bug 856486 - Uplifting to Aurora. a=lsblakk