Initial items: 1) Land wchen's prior patches https://hg.mozilla.org/users/wchen_mozilla.com/shadow-dom/shortlog 2) Event propagation - handle events cross and contained in boundary - implement Event.composedPath https://dom.spec.whatwg.org/#dom-event-composedpath 3) Focus - handle delegateFocus: true & false cases

Please correct me if I'm wrong about this being a meta bug, Ben.

Update: > 1) Land wchen's prior patches (https://hg.mozilla.org/users/wchen_mozilla.com/shadow-dom/shortlog) - node distribution (bug 1409975) > support single level distribution > support multi-level distribution and fallback content > Slot.assignedNodes w/ flatten: true (https://html.spec.whatwg.org/multipage/scripting.html#dom-slot-assignednodes) > handle slot in child iterator (https://hg.mozilla.org/users/wchen_mozilla.com/shadow-dom/rev/f66301e096a7) Besides wchen's patches: - slotchange event (bug 1409976) - support operations on closed-mode shadow root (bug 1411878) > 2) Event propagation (https://dom.spec.whatwg.org/#dispatching-events) - handle events cross and contained in boundary - implement Event.composedPath (https://dom.spec.whatwg.org/#dom-event-composedpath) > 3) Focus (https://w3c.github.io/webcomponents/spec/shadow/#focus) - handle delegateFocus: true & false cases - sequential focus navigation - active element (not in DOM spec yet) > 4) Remove v0 API for wpt (https://w3c-test.org/shadow-dom/historical.html)