Revert "Build Observatory with runtime"

runtime/bin/vmservice/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;
 
 /// A [Page] controls the user interface of Observatory. At any given time
 /// one page will be the current page. Pages are registered at startup.
 /// When the user navigates within the application, each page is asked if it
 /// can handle the current location, the first page to say yes, wins.
@@ skipping 225 matching lines @@
   void _visit(String url) {
     assert(element != null);
     assert(canVisit(url));
     app.vm.get(_isolateId(url)).then((i) {
       (element as MetricsPageElement).isolate = i;
     });
   }
 
   bool canVisit(String url) => _matcher.hasMatch(url);
 }