DevTools: switch Timeline frontend into buffered mode and remove the corresponding experiment.

LayoutTests/inspector/timeline/timeline-network-resource.html

Index: LayoutTests/inspector/timeline/timeline-network-resource.html
diff --git a/LayoutTests/inspector/timeline/timeline-network-resource.html b/LayoutTests/inspector/timeline/timeline-network-resource.html
index 1cae523912ddc761acf1be156b1338bc42574d9d..4bb691b25f496b89473448edcb4bdac0aea357a8 100644
--- a/LayoutTests/inspector/timeline/timeline-network-resource.html
+++ b/LayoutTests/inspector/timeline/timeline-network-resource.html
@@ -6,8 +6,9 @@
 
 var scriptUrl = "timeline-network-resource.js";
 
-function performActions() 
+function performActions(callback) 
 {
+    window.timelineNetworkResourceEvaluated = callback;
     var script = document.createElement("script");
     script.src = scriptUrl;
     document.body.appendChild(script);
@@ -21,20 +22,9 @@ function test()
     var model = WebInspector.panels.timeline._model;
     var presentationModel = InspectorTest.timelinePresentationModel();
 
-    InspectorTest.startTimeline(step1);
+    InspectorTest.invokeAsyncWithTimeline("performActions", finish);
 
-    function step1()
-    {
-        InspectorTest.evaluateInPage("performActions()");
-    }
-
-    // It will be called from timeline-network-resource.js script by evaluateInWebInspector call.
-    InspectorTest.scriptEvaluated = function()
-    {
-        InspectorTest.stopTimeline(step3);
-    }
-
-    function step3()
+    function finish()
     {
         var lastRecordStartTime;
         function format(record)