DevTools: add more jsdocs to NetworkPanel.

Source/devtools/front_end/profiler/CanvasProfileView.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 501 matching lines @@
             callViewElement.appendChild(WebInspector.CanvasProfileDataGridHelper.createCallArgumentElement(call.result));
         }
 
         var node = new WebInspector.DataGridNode(data);
         node.index = index;
         node.selectable = true;
         node.call = call;
         return node;
     },
 
+    /**
+     * @param {!Element} element
+     * @param {!Event} event
+     * @return {!Element|!AnchorBox|undefined}
+     */
     _popoverAnchor: function(element, event)
     {
         var argumentElement = element.enclosingNodeOrSelfWithClass("canvas-call-argument");
         if (!argumentElement || argumentElement.__suppressPopover)
-            return null;
+            return;
         return argumentElement;
     },
 
     _resolveObjectForPopover: function(argumentElement, showCallback, objectGroupName)
     {
         /**
          * @param {?Protocol.Error} error
          * @param {!RuntimeAgent.RemoteObject=} result
          * @param {!CanvasAgent.ResourceState=} resourceState
          * @this {WebInspector.CanvasProfileView}
@@ skipping 730 matching lines @@
     },
 
     clearResourceStates: function()
     {
         this._currentResourceStates = {};
         this.dispatchEventToListeners(WebInspector.CanvasTraceLogPlayerProxy.Events.CanvasReplayStateChanged);
     },
 
     __proto__: WebInspector.Object.prototype
 }