dart2js: is-checks for the new emitter.

pkg/compiler/lib/src/js_emitter/old_emitter/container_builder.dart

Index: pkg/compiler/lib/src/js_emitter/old_emitter/container_builder.dart
diff --git a/pkg/compiler/lib/src/js_emitter/old_emitter/container_builder.dart b/pkg/compiler/lib/src/js_emitter/old_emitter/container_builder.dart
index 5039711dc44c0e14e71ad264ac8f342c6210bab6..981ed489d31d8285a91eb1fc3f0aca80020f45d2 100644
--- a/pkg/compiler/lib/src/js_emitter/old_emitter/container_builder.dart
+++ b/pkg/compiler/lib/src/js_emitter/old_emitter/container_builder.dart
@@ -125,8 +125,10 @@ class ContainerBuilder extends CodeEmitterHelper {
         // Instead we need to call the statically resolved target.
         //   `<class>.prototype.bar$1.call(this, argument0, ...)`.
         body = js.statement(
-            'return #.prototype.#.call(this, #);',
-            [backend.emitter.classAccess(superClass), methodName,
+            'return #.#.call(this, #);',
+            [backend.emitter.prototypeAccess(superClass,
+                                             hasBeenInstantiated: true),
+             methodName,
              argumentsBuffer]);
       } else {
         body = js.statement(