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

LayoutTests/inspector/timeline/timeline-gc-event.html

Index: LayoutTests/inspector/timeline/timeline-gc-event.html
diff --git a/LayoutTests/inspector/timeline/timeline-gc-event.html b/LayoutTests/inspector/timeline/timeline-gc-event.html
index a7d19354f6987bf40acc4dd52005d0aac06d99e1..3936a676f0c27e03cd7761adededd474d4a178d1 100644
--- a/LayoutTests/inspector/timeline/timeline-gc-event.html
+++ b/LayoutTests/inspector/timeline/timeline-gc-event.html
@@ -18,13 +18,12 @@ function test()
 
     function validate(records)
     {
-        for (var i = 0; i < records.length; ++i) {
-            var record = records[i];
-            if (record.type === WebInspector.TimelineModel.RecordType.GCEvent) {
-                InspectorTest.addResult("The expected GC event record");
-                InspectorTest.addObject(record, InspectorTest.timelinePropertyFormatters);
-                break;
-            }
+        var gcRecords = InspectorTest.filterTimelineRecords(WebInspector.TimelineModel.RecordType.GCEvent, true);
+        if (gcRecords.length) {
+            InspectorTest.addResult("The expected GC event record");
+            InspectorTest.addObject(gcRecords[0], InspectorTest.timelinePropertyFormatters);
+        } else {
+            InspectorTest.addResult("FAILED: GC event record wasn't found");
         }
 
         InspectorTest.completeTest();