[DevTools] Remove SidebarTreeElement from SecurityPanel.

third_party/WebKit/LayoutTests/http/tests/inspector/security-test.js

 var initialize_SecurityTest = function() {
 
 InspectorTest.preloadPanel("security");
 
 InspectorTest.dumpSecurityPanelSidebarOrigins = function() {
     for (var key in WebInspector.SecurityPanelSidebarTree.OriginGroupName) {
         var originGroupName = WebInspector.SecurityPanelSidebarTree.OriginGroupName[key];
-        var originTitles = WebInspector.SecurityPanel._instance()._sidebarTree._originGroups.get(originGroupName).childrenListElement.getElementsByClassName("title");
-        if (originTitles.length > 0) {
-            InspectorTest.addResult("Group: " + originGroupName);
-            for (var originTitle of originTitles)
-                InspectorTest.dumpDeepInnerHTML(originTitle);
-        }
+        var originGroup = WebInspector.SecurityPanel._instance()._sidebarTree._originGroups.get(originGroupName);
+        if (originGroup.hidden)
+            continue;
+        InspectorTest.addResult("Group: " + originGroupName);
+        var originTitles = originGroup.childrenListElement.getElementsByClassName("title");
+        for (var originTitle of originTitles)
+            InspectorTest.dumpDeepInnerHTML(originTitle);
     }
 }
 
 /**
  * @param {!WebInspector.NetworkRequest} request
  */
 InspectorTest.dispatchRequestFinished = function(request) {
     InspectorTest.networkManager.dispatchEventToListeners(WebInspector.NetworkManager.Events.RequestFinished, request);
 }
 
 }