Update to polymer js version 0.4.1

pkg/polymer/lib/src/property_accessor.dart

Index: pkg/polymer/lib/src/property_accessor.dart
diff --git a/pkg/polymer/lib/src/property_accessor.dart b/pkg/polymer/lib/src/property_accessor.dart
index b639b47a3b9612f3fbf33599e6fc26b0eb2d34c5..9903d55d3ae42000f3650d30110e66b83d59d2e7 100644
--- a/pkg/polymer/lib/src/property_accessor.dart
+++ b/pkg/polymer/lib/src/property_accessor.dart
@@ -51,6 +51,9 @@ class _PropertyAccessor<T> {
   }
 
   set value(T newValue) {
+    // Dart Note: The js side makes computed properties read only, and bails
+    // out right here for them (ignoreWrites). For us they are automatically
+    // read only unless you define a setter for them, so we left that out.
     if (bindable != null) {
       bindable.value = newValue;
     } else {