DevTools: adopt existing Timeline tests for tracing based Timeline

Source/devtools/front_end/components/InspectorView.js

Index: Source/devtools/front_end/components/InspectorView.js
diff --git a/Source/devtools/front_end/components/InspectorView.js b/Source/devtools/front_end/components/InspectorView.js
index 3ec314b2996073faf2750be01230e94c5363677b..4d21088f6a814cf250b9b50804bc59408dae12bb 100644
--- a/Source/devtools/front_end/components/InspectorView.js
+++ b/Source/devtools/front_end/components/InspectorView.js
@@ -81,6 +81,11 @@ WebInspector.InspectorView = function()
     this._closeBracketIdentifiers = ["U+005D", "U+00DD"].keySet();
     this._lastActivePanelSetting = WebInspector.settings.createSetting("lastActivePanel", "elements");
 
+    if ("tracing" === this._lastActivePanelSetting.get()) {
+        WebInspector.experimentsSettings.timelineOnTraceEvents.setEnabled(true);
+        this._lastActivePanelSetting.set("timeline");
+    }
+
     this._loadPanelDesciptors();
 
     InspectorFrontendHost.events.addEventListener(InspectorFrontendHostAPI.Events.ShowConsole, this.showPanel.bind(this, "console"));