Misc Observatory patches:

runtime/observatory/lib/src/elements/heap_snapshot.dart

 // Copyright (c) 2015, 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.
 
 library heap_snapshot_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'observatory_element.dart';
-import 'heap_profile.dart';
 import 'package:observatory/app.dart';
 import 'package:observatory/service.dart';
 import 'package:observatory/elements.dart';
 import 'package:observatory/object_graph.dart';
-import 'package:logging/logging.dart';
 import 'package:polymer/polymer.dart';
 
 class DominatorTreeRow extends TableTreeRow {
   final ObjectVertex vertex;
   final HeapSnapshot snapshot;
 
   var _domTreeChildren;
   get domTreeChildren {
     if (_domTreeChildren == null) {
       _domTreeChildren = vertex.dominatorTreeChildren();
@@ skipping 428 matching lines @@
 
     new Future.delayed(const Duration(milliseconds: 500), () {
       buildMergedVertices(snapshot.graph).then((vertices) {
         state = 'Loaded';
         var rootRow = new MergedVerticesRow(tree, null, isolate, vertices);
         tree.initialize(rootRow);
       });
     });
   }
 }