Report arity errors on user definable operators.

sdk/lib/_internal/compiler/implementation/util/link.dart

 // Copyright (c) 2011, 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.
 
 part of org_dartlang_compiler_util;
 
 class Link<T> extends Iterable<T> {
   T get head => null;
   Link<T> get tail => null;
 
@@ skipping 31 matching lines @@
 
   bool get isEmpty => true;
 
   Link<T> reverse() => this;
 
   Link<T> reversePrependAll(Link<T> from) {
     if (from.isEmpty) return this;
     return this.prepend(from.head).reversePrependAll(from.tail);
   }
 
+  Link<T> skip(int n) {
+    if (n == 0) return this;
+    throw new RangeError('Index $n out of range');
+  }
+
   void forEach(void f(T element)) {}
 
   bool operator ==(other) {
     if (other is !Link<T>) return false;
     return other.isEmpty;
   }
 
   String toString() => "[]";
 
   get length {
     throw new UnsupportedError('get:length');
   }
 }
 
 abstract class LinkBuilder<T> {
   factory LinkBuilder() = LinkBuilderImplementation;
 
   Link<T> toLink();
   void addLast(T t);
 
   final int length;
   final bool isEmpty;
 }