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

lib/src/common/js_proxy.dart

Index: lib/src/common/js_proxy.dart
diff --git a/lib/src/common/js_proxy.dart b/lib/src/common/js_proxy.dart
index 3bc7b81b9b0d58a014aff3660140c55515ecaad8..276d378c81151c9c7db3165ed4a4dd2b94c97b6f 100644
--- a/lib/src/common/js_proxy.dart
+++ b/lib/src/common/js_proxy.dart
@@ -5,6 +5,7 @@ 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!
@@ -59,7 +60,12 @@ 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 = {