Implement unresolved super-send (but ignoring arguments).

dart/frog/leg/resolver.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
 }
 
 class TreeElementMapping implements TreeElements {
@@ skipping 750 matching lines @@
     allowedCategory |=
       ElementCategory.CLASS | ElementCategory.PREFIX | ElementCategory.SUPER;
     Element resolvedReceiver = visit(node.receiver);
     allowedCategory = oldCategory;
 
     Element target;
     SourceString name = node.selector.asIdentifier().source;
     if (name.stringValue === 'this') {
       error(node.selector, MessageKind.GENERIC, ["expected an identifier"]);
     } else if (node.isSuperCall) {
-      if (isUserDefinableOperator(name.stringValue)) {
-        name = Elements.constructOperatorName(const SourceString('operator'),
-                                              name);
+      if (node.isOperator) {
+        if (isUserDefinableOperator(name.stringValue)) {
+          name = Elements.constructOperatorName(const SourceString('operator'),
+                                                name);
+        } else {
+          error(node.selector, MessageKind.ILLEGAL_SUPER_SEND, [name]);
+        }
       }
       if (!inInstanceContext) {
         error(node.receiver, MessageKind.NO_INSTANCE_AVAILABLE, [name]);
         return null;
       }
       if (currentClass.supertype === null) {
         // This is just to guard against internal errors, so no need
         // for a real error message.
         error(node.receiver, MessageKind.GENERIC, ["Object has no superclass"]);
       }
@@ skipping 992 matching lines @@
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) {
     return library.find(name);
   }
 
   Element add(Element element) {
     throw "Cannot add an element in the top scope";
   }
 }