DevTools: remove old Timeline front-end implementation

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 17 matching lines @@
     root: "formatAsTypeName",
     backendNodeId: "formatAsTypeName",
     nodeId: "formatAsTypeName",
     rootNode: "formatAsTypeName",
     networkTime: "formatAsTypeName",
     thread: "formatAsTypeName"
 };
 
 InspectorTest.switchTimelineToWaterfallMode = function()
 {
-    if (!Runtime.experiments.isEnabled("timelineOnTraceEvents"))
-        return;
     if (WebInspector.panels.timeline._flameChartToggleButton.toggled)
         WebInspector.panels.timeline._flameChartToggleButton.element.click();
 }
 
 InspectorTest.timelinePresentationModel = function()
 {
     InspectorTest.switchTimelineToWaterfallMode();
     return WebInspector.panels.timeline._currentViews[0]._presentationModel;
 }
 
@@ skipping 318 matching lines @@
         return this._fileSize;
     },
 
     fileName: function()
     {
         return "fakeFile";
     }
 };
 
 };