Bug 1383076 - restore workaround for 'current' setter on panelviews in non-photon panelmultiview, r=mconley

MozReview-Commit-ID: 6YZ6Wyu0Spc

--HG--
extra : rebase_source : 69df1d25835a817e37e5e852b68792aa8f506887

browser/components/extensions/ext-browserAction.js

@@ -181,6 +181,12 @@ this.browserAction = class extends ExtensionAPI {
         // Google Chrome onClicked extension API.
         if (popupURL) {
           try {
+            if (event.target.closest("panelmultiview")) {
+              // FIXME: The line below needs to change eventually, but for now:
+              // ensure the view is _always_ visible _before_ `popup.attach()` is
+              // called. PanelMultiView.jsm dictates different behavior.
+              event.target.setAttribute("current", true);
+            }
             let popup = this.getPopup(document.defaultView, popupURL);
             let attachPromise = popup.attach(event.target);
             event.detail.addBlocker(attachPromise);