Enhance workspace tab initialization and update tab toolbar on load

src/browser/base/content/ZenUIManager.mjs

@@ -27,6 +27,7 @@ var gZenUIManager = {
 
     SessionStore.promiseAllWindowsRestored.then(() => {
       this._hasLoadedDOM = true;
+      this.updateTabsToolbar();
     });
 
     window.addEventListener('TabClose', this.onTabClose.bind(this));