update to polymer js 0.5.1

pkg/polymer/test/prop_attr_reflection_test.dart

Index: pkg/polymer/test/prop_attr_reflection_test.dart
diff --git a/pkg/polymer/test/prop_attr_reflection_test.dart b/pkg/polymer/test/prop_attr_reflection_test.dart
index cf260f55a5acc565bba977a832461c241f855b1b..7e0ab6dc30630bab0b410d4abd8b50ea9ca04a7d 100644
--- a/pkg/polymer/test/prop_attr_reflection_test.dart
+++ b/pkg/polymer/test/prop_attr_reflection_test.dart
@@ -176,7 +176,7 @@ main() => initPolymer().run(() {
     }).then((_) => onAttributeChange(xzot)).then((_) {
       expect(xzot.attributes['str'], xzot.str);
       // TODO(jmesserly): the JS test seems backwards of the description text.
-      // Is it because it doesn't do "Platform.flush()"?
+      // Is it because it doesn't do "WebComponents.flush()"?
       expect(xzot.attributes['zot'], '5',
           reason: 'extendee reflect false not honored');
     });