First cut at behaviors. This just implements the lifecycle methodsportion. We may get the rest for …

lib/src/common/js_proxy.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.
 library polymer.lib.src.common.js_proxy;
 
 import 'dart:js';
 import 'package:reflectable/reflectable.dart';
+import 'behavior.dart';
 import 'declarations.dart';
 
 // Mixin this class to get js proxy support!
 abstract class JsProxy {
   /// Lazily create proxy constructors!
   static Map<Type, JsFunction> _jsProxyConstructors = {};
 
   /// Never reads from the dart object, instead reads properties from the
   /// `__cache__` object. This is primarily useful for objects that you pass in
   /// empty, and the javascript code will populate. It should be used carefully
@@ skipping 34 matching lines @@
 const jsProxyReflectable = const JsProxyReflectable();
 
 final JsObject _polymerDart = context['Polymer']['Dart'];
 
 /// Given a dart type, this creates a javascript constructor and prototype
 /// which can act as a proxy for it.
 JsFunction _buildJsConstructorForType(Type dartType) {
   var constructor = _polymerDart.callMethod('functionFactory');
   var prototype = new JsObject(context['Object']);
 
-  var declarations = declarationsFor(dartType, jsProxyReflectable);
+  var declarations = declarationsFor(
+      dartType, jsProxyReflectable, where: (name, declaration) {
+    // Skip declarations from [BehaviorProxy] classes. These should not
+    // read/write from the dart class.
+    return !declaration.owner.metadata.any((m) => m is BehaviorProxy);

[Siggi Cherem (dart-lang), 2015/08/13 18:52:41]

should we have a type to declare things that don't require the js constructor?
(BehaviorProxy is currently the only one, but wouldn't that be necessary for any
other mixin that relies on code from JS?) I guess maybe there is nothing else
like it in the polymer.js world?

[jakemac, 2015/08/13 19:14:29]

Nothing else that I know of today, I think we can add that if needed later on.

+  });
   declarations.forEach((String name, DeclarationMirror declaration) {
     if (isProperty(declaration)) {
       var descriptor = {
         'get': _polymerDart.callMethod('propertyAccessorFactory', [
           name,
           (dartInstance) {
             var mirror = jsProxyReflectable.reflect(dartInstance);
             return jsValue(mirror.invokeGetter(name));
           }
         ]),
@@ skipping 109 matching lines @@
       {'configurable': false, 'enumerable': false, 'writeable': false,});
   // Don't want to jsify the instance, if its a map that will make turn it into
   // a JsObject.
   details['value'] = dartInstance;
   context['Object'].callMethod(
       'defineProperty', [jsObject, '__dartClass__', details]);
 }
 
 /// Gets a reference to the original dart instance from a js proxy object.
 dynamic _getDartInstance(JsObject jsObject) => jsObject['__dartClass__'];