Bug 1864957 - remove the extra <panel> Report Broken Site was using as a work-around for bug 1866503; r=Gijs,desktop-theme-reviewers,dao

Differential Revision: https://phabricator.services.mozilla.com/D196121

Author: wisniewskit

browser/components/reportbrokensite/ReportBrokenSite.sys.mjs

@@ -700,11 +700,9 @@ export var ReportBrokenSite = new (class ReportBrokenSite {
         const appMenuPopup = document.getElementById("appMenu-popup");
         appMenuPopup?.hidePopup();
 
-        // See bug 1864957; we should be able to use showSubView here
-        ownerGlobal.PanelMultiView.openPopup(
-          document.getElementById("report-broken-main-menu-panel"),
-          document.getElementById("PanelUI-menu-button"),
-          { position: "bottomright topright" }
+        ownerGlobal.PanelUI.showSubView(
+          ReportBrokenSite.MAIN_PANELVIEW_ID,
+          ownerGlobal.PanelUI.menuButton
         );
         break;
     }

browser/components/reportbrokensite/content/reportBrokenSitePanel.inc.xhtml

@@ -2,27 +2,15 @@
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 
-<panel id="report-broken-main-menu-panel"
-       class="cui-widget-panel panel-no-padding"
-       type="arrow"
-       role="alertdialog"
-       aria-labelledby="report-broken-site-panel-intro"
-       noautofocus="true"
-       tabspecific="true"
-       flip="slide"
-       orient="vertical">
-  <panelmultiview mainViewId="report-broken-site-popup-mainView"/>
-</panel>
-
 <panelview id="report-broken-site-popup-mainView"
            class="report-broken-site-view main-view PanelUI-subView"
            role="document"
            data-l10n-id="report-broken-site-panel-header"
            data-l10n-attrs="title"
            hidden="true"
            showheader="true">
-  <!-- Once bug 1864957 is fixed, the wants-back-button attribute here
-       should probably be removed, as well as in PanelMultiView.sys.mjs.
+  <!-- wants-back-button will be removed in bug 1869574
+       (and also from PanelMultiView.sys.mjs)
   -->
   <box class="panel-header" wants-back-button="true">
     <html:h1 role="heading" aria-level="1">

browser/themes/shared/customizableui/panelUI-shared.css

@@ -433,8 +433,7 @@ panelview[id^=PanelUI-webext-] {
 /* The Report Broken Site panel can be opened from the Help menu
  * in the menubar, which isn't a descendant of #appMenu-popup.
  * Target it specifically in this rule to make it the same width
- * as if it was a standard panelview opened from the app menu.
- * This hack should probably be removed once bug 1864957 is fixed. */
+ * as if it was a standard panelview opened from the app menu. */
 #report-broken-site-popup-mainView[mainview],
 #PanelUI-fxa {
   width: 22.5em;