Comment on attachment 820828 [details] [diff] [review] Implement web components ShadowRoot style sheet behavior. Review of attachment 820828 [details] [diff] [review]: ----------------------------------------------------------------- This looks really good. Just a couple of small comments. ::: content/base/src/ShadowRoot.cpp @@ +139,5 @@ > + > + mProtoBinding->FlushSkinSheets(); > + > + nsIPresShell* shell = OwnerDoc()->GetShell(); > + if (shell) { I think it's worth making a helper function for this (RestyleShadowRoot()) and sharing it between Insert/RemoveSheet. ::: content/html/content/src/HTMLStyleElement.cpp @@ +161,2 @@ > nsGenericHTMLElement::UnbindFromTree(aDeep, aNullParent); > + UpdateStyleSheetInternal(oldDoc, oldShadow); Nit: no need for single-use |oldShadow|. ::: content/svg/content/src/SVGStyleElement.cpp @@ +86,2 @@ > SVGStyleElementBase::UnbindFromTree(aDeep, aNullParent); > + UpdateStyleSheetInternal(oldDoc, nullptr); I asked you about this on IRC and you said that it's probably OK to pass null for the oldShadowRoot. Please add a comment why or simply pass in the shadow root as you said that'd also work and should be harmless.