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

lib/src/js/polymer_bind_dart.html

+<!--
+Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file

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

+1 :)

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

Done.

+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.
+-->
 <script>
 if (Polymer.Bind) {
   // Overwrite prepareInstance to a no-op for dart elements.
   Polymer.Bind._originalPrepareInstance = Polymer.Bind.prepareInstance;
   Polymer.Bind.prepareInstance = function (inst) {
     if (inst.__isPolymerDart__) return;
     this._originalPrepareInstance(inst);
-  }
+  };
 
   // We always need to create property accessors for dart elements, because we
   // always have `effects` (updating the dart class).
   // TODO(jakemac): Investigate making the updating of the dart class be an
   // actual `effect` so that we don't have to do this hack.
   Polymer.Bind.oldCreateBindings = Polymer.Bind.createBindings;
   Polymer.Bind.createBindings = function(model) {
     if (!model.__isPolymerDart__) {
       this.oldCreateBindings(model);
       return;
     }
 
     // map of properties to effects
     var fx$ = model._propertyEffects || {};
     var p$ = model.properties;
-    // for each property with effects
-    for (var n in p$) {
+
+    // The union of the keys in fx$ and p$ (fx$ might contain properties from
+    // js behaviors, which don't appear in p$).
+    var allProperties = {};
+    for (var key in p$) {
+      allProperties[key] = true;
+    }
+    for (var key in fx$) {
+      allProperties[key] = true;
+    }
+
+    // for each dart property (with or without effects) and each js property
+    // with effects
+    for (var n in allProperties) {
       // array of effects
       var fx = fx$[n];
       // effects have priority
       if (fx) {
         fx.sort(this._sortPropertyEffects);
       }
       // create accessors
       this._createAccessors(model, n, fx);
     }
   };
 }
 </script>