Handle super-method invocations in CPS->JS backend.

pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart

Index: pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
diff --git a/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart b/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
index 26a0fa57e735e696a91fcfa490e0838bf6abc0bc..7adc39fb50501a0f44d5d99112d8f3f2aebcd573 100644
--- a/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
+++ b/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
@@ -777,8 +777,12 @@ class ASTEmitter
   }
 
   @override
-  Expression visitInvokeSuperMethod(tree.InvokeSuperMethod exp,
-                                    BuilderContext<Statement> context) {
+  Expression visitInvokeMethodDirectly(tree.InvokeMethodDirectly exp,
+                                       BuilderContext<Statement> context) {
+    // When targeting Dart, InvokeMethodDirectly is only used for super calls.
+    // The receiver is known to be `this`, and the target method is a method
+    // on the super class. So we just translate it as a method call with the
+    // super receiver.
     return emitMethodCall(exp, new SuperReceiver(), context);
   }