Start timeline recording using TimelinePanel methods instead of agent methods

LayoutTests/http/tests/inspector/timeline-test.js

 var initialize_Timeline = function() {
 
 // Scrub values when printing out these properties in the record or data field.
 InspectorTest.timelinePropertyFormatters = {
     children: "formatAsTypeName",
     endTime: "formatAsTypeName",
     requestId: "formatAsTypeName",
     startTime: "formatAsTypeName",
     stackTrace: "formatAsTypeName",
     url: "formatAsURL",
@@ skipping 23 matching lines @@
 }
 
 InspectorTest.timelineModel = function()
 {
     return WebInspector.panels.timeline._model;
 }
 
 InspectorTest.startTimeline = function(callback)
 {
     var panel = WebInspector.inspectorView.panel("timeline");
-    panel.toggleTimelineButton.toggled = true;
-    panel._model._collectionEnabled = true;
-    panel._userInitiatedRecording = true;
-    panel._model._currentTarget = WebInspector.targetManager.mainTarget();
-    TimelineAgent.start(5, true, undefined, true, false, callback);
+    function onRecordingStarted()
+    {
+        panel._model.removeEventListener(WebInspector.TimelineModel.Events.RecordingStarted, onRecordingStarted, this)
+        callback();
+    }
+    panel._model.addEventListener(WebInspector.TimelineModel.Events.RecordingStarted, onRecordingStarted, this)
+    panel.toggleTimelineButton.element.click();
 };
 
 InspectorTest.stopTimeline = function(callback)
 {
-    function didStop(error)
+    var panel = WebInspector.inspectorView.panel("timeline");
+    function didStop()
     {
-        if (error)
-            testRunner.logToStderr("error: " + error);
-        var panel = WebInspector.inspectorView.panel("timeline");
-        panel.toggleTimelineButton.toggled = false;
-        panel._userInitiatedRecording = false;
+        panel._model.removeEventListener(WebInspector.TimelineModel.Events.RecordingStopped, didStop, this)
         callback();
     }
-    TimelineAgent.stop(didStop);
+    panel._model.addEventListener(WebInspector.TimelineModel.Events.RecordingStopped, didStop, this)
+    panel.toggleTimelineButton.element.click();
 };
 
 InspectorTest.evaluateWithTimeline = function(actions, doneCallback)
 {
     InspectorTest.startTimeline(step1);
     function step1()
     {
         InspectorTest.evaluateInPage(actions, step2);
     }
 
@@ skipping 259 matching lines @@
         return this._fileSize;
     },
 
     fileName: function()
     {
         return "fakeFile";
     }
 };
 
 };