DevTools: merge TracingTimelineModel into TimelineModel

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

 var initialize_Timeline = function() {
 
 InspectorTest.preloadPanel("timeline");
 
 // Scrub values when printing out these properties in the record or data field.
 InspectorTest.timelinePropertyFormatters = {
     children: "formatAsTypeName",
     endTime: "formatAsTypeName",
     requestId: "formatAsTypeName",
     startTime: "formatAsTypeName",
@@ skipping 248 matching lines @@
     var object = {};
     var names = ["data", "endTime", "frameId", "stackTrace", "startTime", "thread", "type"];
     for (var i = 0; i < names.length; i++) {
         var name = names[i];
         var value = record[name].call(record)
         if (value)
             object[name] = value;
     }
     if (record.children().length)
         object["children"] = [];
-    if (!record.data() && record instanceof WebInspector.TracingTimelineModel.TraceEventRecord)
+    if (!record.data())
         object["data"] = record.traceEvent().args;
     InspectorTest.addObject(object, InspectorTest.timelinePropertyFormatters);
 };
 
 InspectorTest.findFirstTimelineRecord = function(type)
 {
     return InspectorTest.findTimelineRecord(type, 0);
 }
 
 // Find the (n+1)th timeline record of a specific type.
@@ skipping 81 matching lines @@
         return this._fileSize;
     },
 
     fileName: function()
     {
         return "fakeFile";
     }
 };
 
 };