This tracks issues blocking pref-ing on image srcset landing in bug 870021
Please submit to the release notes once we have an idea in which release it is going to ship. Thanks
Release Note Request (optional, but appreciated) [Why is this notable]: responsive images – also see Bug 1017875 [Suggested wording]: Implemented srcset attribute and <picture> element for responsive images [Links (documentation, blog post, etc)]: Since this and Bug 1017875 are closely connected, a singular entry in the Release Notes should suffice.
this was noted from bug 1017875 as: Implemented srcset attribute and <picture> element for responsive images