As of today (March 18th 2019), I intend to turn CSS Containment <https://drafts.csswg.org/css-contain/> on by default on all platforms, in Firefox Nightly 68. It has been developed behind the 'layout.css.contain.enabled' preference.
Other UAs shipping this or intending to ship it are: * Chrome & other Blink-based UAs (Chrome has supported since Chrome 52, released in 2016, according to caniuse <https://caniuse.com/#search=contain> ). Bug to turn on by default: * https://bugzilla.mozilla.org/show_bug.cgi?id=1532471 is where I'll be turning it on in Nightly by default (with a guard to only let it ship as far as early-beta) * https://bugzilla.mozilla.org/show_bug.cgi?id=1487493 is where I'll be removing the guard & letting it ride the trains to release, assuming everything goes well. (I anticipate that this will happen for the Firefox 68 release cycle.) This feature was previously discussed in this "intent to implement" thread: https://groups.google.com/d/msg/mozilla.dev.platform/q-uXVVClcU4/WswhXtlWqFIJ (though the spec and the feature have evolved a good deal since then) Note: we don't currently intend to ship support for one of the keywords mentioned in the spec & which Chrome sort-of supports -- "contain:style". Chrome doesn't implement this keyword properly/robustly, and we have doubts about whether the complexity & maintenance burden of a correct implementation would be justified by this keyword's limited use cases. See https://github.com/w3c/csswg-drafts/issues/3280 for more on this. The CSS Working group has marked this keyword as "at-risk", as a result of the discussion around these concerns. Many thanks to former-interns Morgan Reschenberg, Yusuf Sermet, and Kyle Zentner for their hard work on this feature! _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
