DevTools: DataGrid: corner td should also have regular td style.

BUG=

Review URL: https://codereview.chromium.org/463043002

git-svn-id: svn://svn.chromium.org/blink/trunk@180156 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/devtools/front_end/ui/DataGrid.js

@@ -1176,11 +1176,9 @@ WebInspector.DataGridNode.prototype = {
     {
         this._element.removeChildren();
         var columnsArray = this.dataGrid._visibleColumnsArray;
-        for (var i = 0; i < columnsArray.length; ++i) {
-            var cell = this.createCell(columnsArray[i].identifier);
-            this._element.appendChild(cell);
-        }
-        this._element.createChild("td", "corner");
+        for (var i = 0; i < columnsArray.length; ++i)
+            this._element.appendChild(this.createCell(columnsArray[i].identifier));
+        this._element.appendChild(this._createTDWithClass("corner"));
     },
 
     get data()
@@ -1320,17 +1318,25 @@ WebInspector.DataGridNode.prototype = {
     },
 
     /**
-     * @param {string} columnIdentifier
+     * @param {string} className
      * @return {!Element}
      */
-    createTD: function(columnIdentifier)
+    _createTDWithClass: function(className)
     {
-        var cell = document.createElement("td");
-        cell.className = columnIdentifier + "-column";
+        var cell = document.createElementWithClass("td", className);
         var cellClass = this.dataGrid._cellClass;
         if (cellClass)
             cell.classList.add(cellClass);
+        return cell;
+    },
 
+    /**
+     * @param {string} columnIdentifier
+     * @return {!Element}
+     */
+    createTD: function(columnIdentifier)
+    {
+        var cell = this._createTDWithClass(columnIdentifier + "-column");
         cell.columnIdentifier_ = columnIdentifier;
 
         var alignment = this.dataGrid._columns[columnIdentifier].align;