Add destroy method to I18n module

src/editor/model/Editor.js

@@ -763,7 +763,8 @@ export default Backbone.Model.extend({
       BlockManager,
       CodeManager,
       Commands,
-      DeviceManager
+      DeviceManager,
+      I18n
     } = this.attributes;
     this.stopDefault();
     DomComponents.destroy();
@@ -779,6 +780,7 @@ export default Backbone.Model.extend({
     CodeManager.destroy();
     Commands.destroy();
     DeviceManager.destroy();
+    I18n.destroy();
     this.view.remove();
     this.stopListening();
     this.clear({ silent: true });

src/i18n/index.js

@@ -242,6 +242,11 @@ export default () => {
     _debug(str, opts = {}) {
       const { em, config } = this;
       (opts.debug || config.debug) && em && em.logWarning(str);
+    },
+
+    destroy() {
+      this.config = config;
+      this.em = {};
     }
   };
 };