Reorganize mdv and observe packages

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.
 
-part of dart.mdv_observe_impl;
+part of observe;
 
 // This code is inspired by ChangeSummary:
 // https://github.com/rafaelw/ChangeSummary/blob/master/change_summary.js
 // ...which underlies MDV. Since we don't need the functionality of
 // ChangeSummary, we just implement what we need for data bindings.
 // This allows our implementation to be much simpler.
 
 // TODO(jmesserly): should we make these types stronger, and require
 // Observable objects? Currently, it is fine to say something like:
 //     var path = new PathObserver(123, '');
@@ skipping 148 matching lines @@
     var last = _lastObserver;
     if (_setObjectProperty(last._object, last._property, value)) {
       // Technically, this would get updated asynchronously via a change record.
       // However, it is nice if calling the getter will yield the same value
       // that was just set. So we use this opportunity to update our cache.
       last.value = value;
     }
   }
 }
 
-// TODO(jmesserly): these should go away in favor of mirrors!
 _getObjectProperty(object, property) {
   if (object is List && property is int) {
     if (property >= 0 && property < object.length) {
       return object[property];
     } else {
       return null;
     }
   }
 
-  // TODO(jmesserly): what about length?
-  if (object is Map) return object[property];
+  if (property is Symbol) {
+    var mirror = reflect(object);
+    try {
+      return mirror.getField(property).reflectee;
+    } catch (e) {}
+  }
 
-  if (object is Observable) return object.getValueWorkaround(property);
+  if (object is Map) {
+    return object[property];
+  }
 
   return null;
 }
 
 bool _setObjectProperty(object, property, value) {
   if (object is List && property is int) {
+    if (property >= 0 && property < object.length) {
+      object[property] = value;
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  if (property is Symbol) {
+    var mirror = reflect(object);
+    try {
+      mirror.setField(property, value);
+      return true;
+    } catch (e) {}
+  }
+
+  if (object is Map) {
     object[property] = value;
-  } else if (object is Map) {
-    object[property] = value;
-  } else if (object is Observable) {
-    (object as Observable).setValueWorkaround(property, value);
-  } else {
-    return false;
+    return true;
   }
-  return true;
+
+  return false;
 }
 
-
 class _PropertyObserver {
   final PathObserver _path;
   final _property;
   final _PropertyObserver _next;
 
   // TODO(jmesserly): would be nice not to store both of these.
   Object _object;
   Object _value;
   StreamSubscription _sub;
 
@@ skipping 62 matching lines @@
 
 final _spacesRegExp = new RegExp(r'\s');
 
 bool _isPathValid(String s) {
   s = s.replaceAll(_spacesRegExp, '');
 
   if (s == '') return true;
   if (s[0] == '.') return false;
   return _pathRegExp.hasMatch(s);
 }