Bug 1583231 - Fix indentation, tooltip use, and CSS of what's new panel and toolbarbutton r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D46931

--HG--
extra : moz-landing-system : lando

browser/base/content/browser.xhtml

@@ -1141,7 +1141,6 @@
                        class="toolbarbutton-1"
                        hidden="true"
                        badged="true"
-                      consumeanchor="PanelUI-button"
                        onmousedown="PanelUI.showSubView('PanelUI-whatsNew', this, event);"
                        onkeypress="PanelUI.showSubView('PanelUI-whatsNew', this, event);"/>
         <toolbarbutton id="PanelUI-menu-button"

browser/components/customizableui/content/panelUI.inc.xul

@@ -861,14 +861,9 @@
 
     <panelview id="PanelUI-whatsNew" class="PanelUI-subView">
       <vbox class="panel-subview-body">
-        <box id="PanelUI-whatsNew-title" class="panel-header">
-          <label/>
-        </box>
         <toolbaritem id="PanelUI-whatsNew-content"
                      orient="vertical"
-                     smoothscroll="false"
-                     flatList="true"
-                     tooltip="bhTooltip">
+                     smoothscroll="false">
           <html:div id="PanelUI-whatsNew-message-container" role="document">
             <!-- What's New messages will be rendered here -->
           </html:div>

browser/components/newtab/lib/ToolbarPanelHub.jsm

@@ -24,7 +24,6 @@ const PROTECTIONS_PANEL_INFOMSG_PREF =
 
 const TOOLBAR_BUTTON_ID = "whats-new-menu-button";
 const APPMENU_BUTTON_ID = "appMenu-whatsnew-button";
-const PANEL_HEADER_SELECTOR = "#PanelUI-whatsNew-title > label";
 
 const BUTTON_STRING_ID = "cfr-whatsnew-button";
 const WHATS_NEW_PANEL_SELECTOR = "PanelUI-whatsNew-message-container";
@@ -428,13 +427,6 @@ class _ToolbarPanelHub {
     const document = win.browser.ownerDocument;
     this.maybeInsertFTL(win);
     this._showElement(document, TOOLBAR_BUTTON_ID, BUTTON_STRING_ID);
-    // The toolbar dropdown panel uses this extra header element that is hidden
-    // in the appmenu subview version of the panel. We only need to set it
-    // when showing the toolbar button.
-    document.l10n.setAttributes(
-      document.querySelector(PANEL_HEADER_SELECTOR),
-      "cfr-whatsnew-panel-header"
-    );
   }
 
   _hideToolbarButton(win) {

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

@@ -1804,7 +1804,6 @@ toolbarpaletteitem[place="menu-panel"] > .subviewbutton-nav::after {
 
 /* What's New panel */
 #customizationui-widget-multiview #PanelUI-whatsNew {
-  min-width: @menuPanelWidth@;
   max-width: @menuPanelWidth@;
 }
 
@@ -1845,28 +1844,12 @@ toolbarpaletteitem[place="menu-panel"] > .subviewbutton-nav::after {
   color: white;
 }
 
-#customizationui-widget-multiview #PanelUI-whatsNew-content {
-  height: 586px;
+panelview[mainview] #PanelUI-whatsNew-content {
+  height: 43em;
 }
 
-#PanelUI-whatsNew-title {
-  display: none;
-}
-
-/**
- * The Applications Menu container has some extra padding that does not
- * exist when the What's New dropdown is shown directly from the toolbar
- */
-#PanelUI-whatsNew-content {
-  margin-top: -6px;
-}
-
-#customizationui-widget-multiview #PanelUI-whatsNew-content {
-  margin: 0;
-}
-
-#customizationui-widget-multiview #PanelUI-whatsNew-title {
-  display: flex;
+#PanelUI-whatsNew .panel-subview-body {
+  padding-top: 0;
 }
 
 #PanelUI-whatsNew .whatsNew-message {