[DevTools] Make resource tree model optional

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

 if (window.GCController)
     GCController.collectAll();
 var initialize_InspectorTest = function() {
 
 var results = [];
 
 function consoleOutputHook(messageType)
 {
     InspectorTest.addResult(messageType + ": " + Array.prototype.slice.call(arguments, 1));
 }
@@ skipping 660 matching lines @@
     return buffer.replace(/\s*at[^()]+\(native\)/g, "");
 }
 
 InspectorTest.hideInspectorView = function()
 {
     WebInspector.inspectorView.element.setAttribute("style", "display:none !important");
 }
 
 InspectorTest.mainFrame = function()
 {
-    return InspectorTest.mainTarget.resourceTreeModel.mainFrame;
+    return WebInspector.ResourceTreeModel.fromTarget(InspectorTest.mainTarget).mainFrame;
 }
 
 InspectorTest.StringOutputStream = function(callback)
 {
     this._callback = callback;
     this._buffer = "";
 };
 
 InspectorTest.StringOutputStream.prototype = {
     open: function(fileName, callback)
@@ skipping 196 matching lines @@
         InspectorTest.LayerTreeAgent = target.layerTreeAgent();
         InspectorTest.NetworkAgent = target.networkAgent();
         InspectorTest.PageAgent = target.pageAgent();
         InspectorTest.ProfilerAgent = target.profilerAgent();
         InspectorTest.RuntimeAgent = target.runtimeAgent();
         InspectorTest.WorkerAgent = target.workerAgent();
 
         InspectorTest.consoleModel = target.consoleModel;
         InspectorTest.networkManager = WebInspector.NetworkManager.fromTarget(target);
         InspectorTest.securityOriginManager = WebInspector.SecurityOriginManager.fromTarget(target);
-        InspectorTest.resourceTreeModel = target.resourceTreeModel;
+        InspectorTest.resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(target);
         InspectorTest.networkLog = WebInspector.NetworkLog.fromTarget(target);
         InspectorTest.debuggerModel = WebInspector.DebuggerModel.fromTarget(target);
         InspectorTest.runtimeModel = target.runtimeModel;
         InspectorTest.domModel = WebInspector.DOMModel.fromTarget(target);
         InspectorTest.cssModel = WebInspector.CSSModel.fromTarget(target);
         InspectorTest.workerManager = target.workerManager;
         InspectorTest.powerProfiler = target.powerProfiler;
         InspectorTest.cpuProfilerModel = target.cpuProfilerModel;
         InspectorTest.heapProfilerModel = target.heapProfilerModel;
         InspectorTest.animationModel = target.animationModel;
@@ skipping 236 matching lines @@
     _output("[page] " + text);
 }
 
 function _output(result)
 {
     if (!outputElement)
         createOutputElement();
     outputElement.appendChild(document.createTextNode(result));
     outputElement.appendChild(document.createElement("br"));
 }