Allow closing notification by tapping backdrop

src/managers/notification-manager.html

@@ -9,6 +9,6 @@
     }
   </style>
   <template>
-    <paper-toast id="toast" text='{{text}}'></paper-toast>
+    <paper-toast id="toast" text='{{text}}' no-cancel-on-outside-click='[[neg]]'></paper-toast>
   </template>
 </dom-module>

src/managers/notification-manager.js

@@ -11,6 +11,12 @@ export default new Polymer({
   behaviors: [nuclearObserver],
 
   properties: {
+    // Otherwise we cannot close a modal when a notification is being shown.
+    neg: {
+      type: Boolean,
+      value: false,
+    },
+
     text: {
       type: String,
       bindNuclear: notificationGetters.lastNotificationMessage,