Timeline: show impl-side frames on the Timeline overview

Source/devtools/front_end/TimelineModel.js

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 36 matching lines @@
 WebInspector.TimelineModel.TransferChunkLengthBytes = 5000000;
 
 WebInspector.TimelineModel.RecordType = {
     Root: "Root",
     Program: "Program",
     EventDispatch: "EventDispatch",
 
     GPUTask: "GPUTask",
 
     BeginFrame: "BeginFrame",
+    ActivateLayerTree: "ActivateLayerTree",
     ScheduleStyleRecalculation: "ScheduleStyleRecalculation",
     RecalculateStyles: "RecalculateStyles",
     InvalidateLayout: "InvalidateLayout",
     Layout: "Layout",
     AutosizeText: "AutosizeText",
     PaintSetup: "PaintSetup",
     Paint: "Paint",
     Rasterize: "Rasterize",
     ScrollLayer: "ScrollLayer",
     DecodeImage: "DecodeImage",
@@ skipping 445 matching lines @@
                 break;
             length += itemLength;
             data.push(item);
             ++this._recordIndex;
         }
         if (this._recordIndex === this._records.length)
             data.push(data.pop() + "]");
         stream.write(data.join(separator), this._writeNextChunk.bind(this));
     }
 }