Update to use one less proxy per element

test/src/common/polymer_descriptor_test.dart

Index: test/src/common/polymer_descriptor_test.dart
diff --git a/test/src/common/polymer_descriptor_test.dart b/test/src/common/polymer_descriptor_test.dart
index 61ba26be20f7ba0279e815ff98e1fdf5def74aeb..ae5167e23d21d5eec017efcc099593f6a342ca0f 100644
--- a/test/src/common/polymer_descriptor_test.dart
+++ b/test/src/common/polymer_descriptor_test.dart
@@ -68,12 +68,14 @@ main() async {
     expect(descriptor['behaviorTwoExposedMethod'] is JsFunction, isTrue);
 
     expect(descriptor['behaviors'], isNotNull);
-    expect(descriptor['behaviors'].length, 4);
-    expect(descriptor['behaviors'][0], context['Foo']['JsBehaviorOne']);
-    expect(descriptor['behaviors'][1], behavior.getBehavior(DartBehaviorOne));
-    expect(descriptor['behaviors'][2], context['Foo']['JsBehaviorTwo']);
-    expect(descriptor['behaviors'][3], behavior.getBehavior(DartBehaviorTwo));
-    expect(descriptor['behaviors'][1], isNot(descriptor['behaviors'][3]));
+    expect(descriptor['behaviors'].length, 5);
+    expect(descriptor['behaviors'][0],
+        context['Polymer']['Dart']['InteropBehavior']);
+    expect(descriptor['behaviors'][1], context['Foo']['JsBehaviorOne']);
+    expect(descriptor['behaviors'][2], behavior.getBehavior(DartBehaviorOne));
+    expect(descriptor['behaviors'][3], context['Foo']['JsBehaviorTwo']);
+    expect(descriptor['behaviors'][4], behavior.getBehavior(DartBehaviorTwo));
+    expect(descriptor['behaviors'][2], isNot(descriptor['behaviors'][3]));
   });
 }