Don't create TimelineModel.RecordImpl in TimelinePresentationModel.js

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

 var initialize_Timeline = function() {
 
 // Scrub values when printing out these properties in the record or data field.
 InspectorTest.timelinePropertyFormatters = {
     children: "formatAsTypeName",
     endTime: "formatAsTypeName",
     requestId: "formatAsTypeName",
     startTime: "formatAsTypeName",
     stackTrace: "formatAsTypeName",
     url: "formatAsURL",
@@ skipping 189 matching lines @@
     for (var i = 0; i < numChildren; ++i) {
         if (filterTypes && filterTypes.indexOf(record.children[i].type) == -1)
             continue;
         InspectorTest.dumpTimelineRecord(record.children[i], detailsCallback, level + 1, filterTypes);
     }
 }
 
 // Dump just the record name, indenting output on separate lines for subrecords
 InspectorTest.dumpPresentationRecord = function(presentationRecord, detailsCallback, level, filterTypes)
 {
-    var record = presentationRecord.record();
+    var record = !presentationRecord.presentationParent() ? null : presentationRecord.record();
     if (typeof level !== "number")
         level = 0;
     var prefix = "";
     var suffix = "";
     for (var i = 0; i < level ; ++i)
         prefix = "----" + prefix;
     if (level > 0)
         prefix = prefix + "> ";
     if (presentationRecord.coalesced()) {
         suffix = " x " + presentationRecord.presentationChildren().length;
-    } else if (record.type() === WebInspector.TimelineModel.RecordType.TimeStamp
-        || record.type() === WebInspector.TimelineModel.RecordType.ConsoleTime) {
+    } else if (record && (record.type() === WebInspector.TimelineModel.RecordType.TimeStamp
+        || record.type() === WebInspector.TimelineModel.RecordType.ConsoleTime)) {
         suffix = " : " + record.data().message;
     }
     if (detailsCallback)
-        suffix += " " + detailsCallback(record);
-    InspectorTest.addResult(prefix + InspectorTest._timelineAgentTypeToString(record.type()) + suffix);
+        suffix += " " + detailsCallback(presentationRecord);
+    var typeString = record ? InspectorTest._timelineAgentTypeToString(record.type()) : "Root";
+    InspectorTest.addResult(prefix + typeString + suffix);
 
     var numChildren = presentationRecord.presentationChildren() ? presentationRecord.presentationChildren().length : 0;
     for (var i = 0; i < numChildren; ++i) {
         if (filterTypes && filterTypes.indexOf(presentationRecord.presentationChildren()[i].record().type()) == -1)
             continue;
         InspectorTest.dumpPresentationRecord(presentationRecord.presentationChildren()[i], detailsCallback, level + 1, filterTypes);
     }
 }
 
 InspectorTest.dumpTimelineRecords = function(timelineRecords)
@@ skipping 101 matching lines @@
         return this._fileSize;
     },
 
     fileName: function()
     {
         return "fakeFile";
     }
 };
 
 };