DevTools: move tracing based Timeline out of experiment

LayoutTests/inspector/timeline/timeline-layout-expected.txt

Index: LayoutTests/inspector/timeline/timeline-layout-expected.txt
diff --git a/LayoutTests/inspector/timeline/timeline-layout-expected.txt b/LayoutTests/inspector/timeline/timeline-layout-expected.txt
index f52c3cc0d1ef7273074a088b930fa1385f657cdf..c99637e8ef8caf83df61f5a0a6d9cf01f427bb9b 100644
--- a/LayoutTests/inspector/timeline/timeline-layout-expected.txt
+++ b/LayoutTests/inspector/timeline/timeline-layout-expected.txt
@@ -8,14 +8,18 @@ text
 Layout Properties:
 {
     data : {
-        backendNodeId : <number>
-        dirtyObjects : 3
-        partialLayout : true
-        root : <object>
-        totalObjects : 8
+        beginData : {
+            dirtyObjects : 3
+            frame : <string>
+            partialLayout : true
+            totalObjects : 8
+        }
+        endData : {
+            root : <object>
+            rootNode : <number>
+        }
     }
     endTime : <number>
-    frameId : <string>
     stackTrace : <object>
     startTime : <number>
     thread : <string>
@@ -24,14 +28,18 @@ Layout Properties:
 Layout Properties:
 {
     data : {
-        backendNodeId : <number>
-        dirtyObjects : 2
-        partialLayout : true
-        root : <object>
-        totalObjects : 11
+        beginData : {
+            dirtyObjects : 2
+            frame : <string>
+            partialLayout : true
+            totalObjects : 11
+        }
+        endData : {
+            root : <object>
+            rootNode : <number>
+        }
     }
     endTime : <number>
-    frameId : <string>
     stackTrace : <object>
     startTime : <number>
     thread : <string>