Add destroy method to StyleManager module

src/editor/model/Editor.js

@@ -768,7 +768,8 @@ export default Backbone.Model.extend({
       Modal,
       Parser,
       SelectorManager,
-      StorageManager
+      StorageManager,
+      StyleManager
     } = this.attributes;
     this.stopDefault();
     DomComponents.destroy();
@@ -789,6 +790,7 @@ export default Backbone.Model.extend({
     Parser.destroy();
     SelectorManager.destroy();
     StorageManager.destroy();
+    StyleManager.destroy();
     this.view.remove();
     this.stopListening();
     this.clear({ silent: true });

src/style_manager/index.js

@@ -414,6 +414,16 @@ export default () => {
     _logNoSector(sectorId) {
       const { em } = this;
       em && em.logWarning(`'${sectorId}' sector not found`);
+    },
+
+    destroy() {
+      [properties, sectors].forEach(coll => {
+        coll.reset();
+        coll.stopListening();
+      });
+      SectView.remove();
+      [c, properties, sectors, SectView].forEach(i => (i = {}));
+      this.em = {};
     }
   };
 };