Backed out changeset 3f3fc23bd73e (bug 1316739) for failing browser-chrome's browser/base/content/test/general/browser_storagePressure_notification.js. r=backout on a CLOSED TREE

browser/components/preferences/in-content/containers.xul

@@ -26,6 +26,8 @@
       hidden="true"
       data-category="paneContainers">
   <label class="header-name" flex="1">&paneContainers.title;</label>
+  <button class="help-button"
+          aria-label="&helpButton.label;"/>
 </hbox>
 
 <!-- Containers -->