Fix bug with extension groups not being filtered

Author: pikinier20

scaladoc/resources/dotty_res/scripts/components/DocumentableList.js

@@ -47,6 +47,13 @@ class DocumentableList extends Component {
               return isElementVisible;
             }).length;
 
+          findRefs("span.groupHeader", listRef).forEach(h => {
+            const headerSiblings = this.state.list.getSectionListElementsRefs(h.parentNode).map(ref => this.state.list.toListElement(ref))
+            const isHeaderVisible = headerSiblings.filter(s => this.state.list.isElementVisible(s, filter)) != 0
+
+            this.toggleDisplayStyles(isHeaderVisible, h)
+          })
+
           this.toggleDisplayStyles(isListVisible, listRef);
 
           return isListVisible;

scaladoc/src/dotty/tools/scaladoc/renderers/MemberRenderer.scala

@@ -287,7 +287,7 @@ class MemberRenderer(signatureRenderer: SignatureRenderer)(using DocContext) ext
             .functionParameters(on.argsLists)
             .asInstanceOf[InlineSignatureBuilder].names.reverse
           val sig = typeSig ++ Signature(Plain(s"(${on.name}: ")) ++ on.signature ++ Signature(Plain(")")) ++ argsSig
-          MGroup(span(sig.map(renderElement)), members.sortBy(_.name).toSeq, on.name)
+          MGroup(span(cls := "groupHeader")(sig.map(renderElement)), members.sortBy(_.name).toSeq, on.name)
       }.toSeq
 
     div(cls := "membersList")(renderTabs(