Cleanup for pkg/observe and pkg/polymer

pkg/observe/lib/src/path_observer.dart

 // Copyright (c) 2013, 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 observe.src.path_observer;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:math' show min;
 @MirrorsUsed(metaTargets: const [Reflectable, ObservableProperty],
     override: 'smoke.mirrors')
 import 'dart:mirrors' show MirrorsUsed;
 
 import 'package:logging/logging.dart' show Logger, Level;
 import 'package:observe/observe.dart';
-import 'package:observe/src/observable.dart' show objectType;
 import 'package:smoke/smoke.dart' as smoke;
 
 /// A data-bound path starting from a view-model or model object, for example
 /// `foo.bar.baz`.
 ///
 /// When [open] is called, this will observe changes to the object and any
 /// intermediate object along the path, and send updated values accordingly.
 /// When [close] is called it will stop observing the objects.
 ///
 /// This class is used to implement `Node.bind` and similar functionality in
@@ skipping 629 matching lines @@
     for (var observer in _observers.values.toList(growable: false)) {
       if (observer._isOpen) observer._check();
     }
 
     _resetNeeded = true;
     scheduleMicrotask(reset);
   }
 }
 
 const int _MAX_DIRTY_CHECK_CYCLES = 1000;