Converted Observatory timeline-page element

runtime/observatory/lib/src/app/page.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of app;
 
 final _allocationProfileRepository = new AllocationProfileRepository();
 final _breakpointRepository = new BreakpointRepository();
 final _classSampleProfileRepository = new ClassSampleProfileRepository();
 final _classRepository = new ClassRepository();
@@ skipping 781 matching lines @@
     });
   }
 
   bool canVisit(Uri uri) => uri.path == 'metrics';
 }
 
 class TimelinePage extends Page {
   TimelinePage(app) : super(app);
 
   void onInstall() {
-    if (element == null) {
-      element = new Element.tag('timeline-page');
-    }
-    assert(element != null);
+    element = new TimelinePageElement(app.vm, app.events, app.notifications,
+                                      queue: app.queue);
   }
 
   void _visit(Uri uri) {
-    assert(element != null);
     assert(canVisit(uri));
   }
 
   bool canVisit(Uri uri) => uri.path == 'timeline';
 }