Bug 1909163 - make select dropdowns more properly tabspecific, r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D219618

browser/base/content/browser.js

@@ -3364,9 +3364,9 @@ var XULBrowserWindow = {
     };
 
     // If the location is changed due to switching tabs,
-    // ensure we close any open tabspecific panels.
+    // ensure we close any open tabspecific popups.
     if (aIsSimulated) {
-      closeOpenPanels("panel[tabspecific='true']");
+      closeOpenPanels(":is(panel, menupopup)[tabspecific='true']");
     }
 
     // Ensure we close any remaining open locationspecific panels

toolkit/actors/SelectParent.sys.mjs

@@ -744,13 +744,13 @@ export class SelectParent extends JSWindowActorParent {
     let menulist = document.createXULElement("menulist");
     menulist.setAttribute("id", "ContentSelectDropdown");
     menulist.setAttribute("popuponly", "true");
-    menulist.setAttribute("tabspecific", "true");
     menulist.setAttribute("hidden", "true");
 
     let popup = menulist.appendChild(document.createXULElement("menupopup"));
     popup.setAttribute("id", "ContentSelectDropdownPopup");
     popup.setAttribute("activateontab", "true");
     popup.setAttribute("position", "after_start");
+    popup.setAttribute("tabspecific", "true");
     popup.setAttribute("level", "parent");
     if (AppConstants.platform == "win") {
       popup.setAttribute("consumeoutsideclicks", "false");