fix PathObserver to avoid try+catch

pkg/observe/lib/src/to_observable.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.
 
-part of observe;
+library observe.src.to_observable;
+
+import 'package:observe/observe.dart';
 
 /**
  * Converts the [Iterable] or [Map] to an [ObservableList] or [ObservableMap],
  * respectively. This is a convenience function to make it easier to convert
  * literals into the corresponding observable collection type.
  *
  * If [value] is not one of those collection types, or is already [Observable],
  * it will be returned unmodified.
  *
  * If [value] is a [Map], the resulting value will use the appropriate kind of
@@ skipping 11 matching lines @@
 _toObservableShallow(value) {
   if (value is Observable) return value;
   if (value is Map) return new ObservableMap.from(value);
   if (value is Iterable) return new ObservableList.from(value);
   return value;
 }
 
 _toObservableDeep(value) {
   if (value is Observable) return value;
   if (value is Map) {
-    var result = new ObservableMap._createFromType(value);
+    var result = new ObservableMap.createFromType(value);
     value.forEach((k, v) {
       result[_toObservableDeep(k)] = _toObservableDeep(v);
     });
     return result;
   }
   if (value is Iterable) {
     return new ObservableList.from(value.map(_toObservableDeep));
   }
   return value;
 }