[Devtools] Cleanup DataGrid's typecast and identifier naming

third_party/WebKit/Source/devtools/front_end/resources/DOMStorageItemsView.js

 /*
  * Copyright (C) 2008 Nokia Inc.  All rights reserved.
  * Copyright (C) 2013 Samsung Electronics. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 164 matching lines @@
         if (error)
             return;
 
         this._dataGrid = this._dataGridForDOMStorageItems(items);
         this._dataGrid.asWidget().show(this.element);
         this.deleteButton.setVisible(this._dataGrid.rootNode().children.length > 1);
     },
 
     _dataGridForDOMStorageItems: function(items)
     {
-        var columns = [
-            {id: "key", title: WebInspector.UIString("Key"), editable: true, weight: 50},
-            {id: "value", title: WebInspector.UIString("Value"), editable: true, weight: 50}
-        ];
+        var columns = /** @type {!Array<!WebInspector.DataGrid.ColumnDescriptor>} */ ([
+            {id: "key", title: WebInspector.UIString("Key"), sortable: false, editable: true, weight: 50},
+            {id: "value", title: WebInspector.UIString("Value"), sortable: false, editable: true, weight: 50}
+        ]);
 
         var nodes = [];
 
         var keys = [];
         var length = items.length;
         for (var i = 0; i < items.length; i++) {
             var key = items[i][0];
             var value = items[i][1];
             var node = new WebInspector.DataGridNode({key: key, value: value}, false);
             node.selectable = true;
@@ skipping 55 matching lines @@
     {
         if (!node || node.isCreationNode)
             return;
 
         if (this.domStorage)
             this.domStorage.removeItem(node.data.key);
     },
 
     __proto__: WebInspector.SimpleView.prototype
 }