Fix all for-in warnings in dart2js

pkg/compiler/lib/src/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 dart2js.util;
 
-class Link<T> {
+class Link<T> implements Iterable<T> {
   T get head => throw new StateError("no elements");
   Link<T> get tail => null;
 
   const Link();
 
   Link<T> prepend(T element) {
     return new LinkEntry<T>(element, this);
   }
 
   Iterator<T> get iterator => new LinkIterator<T>(this);
@@ skipping 95 matching lines @@
   ///
   /// Returns true for the empty list.
   bool every(bool f(T)) {
     for (Link<T> link = this; !link.isEmpty; link = link.tail){
       if (!f(link.head)) return false;
     }
     return true;
   }
 
   Link copyWithout(e) => this;
+
+  //
+  // Unsupported Iterable<T> methods.
+  //
+  bool any(bool f(T e)) => _unsupported('any');
+  T elementAt(int i) =>  _unsupported('elementAt');
+  Iterable expand(Iterable f(T e)) => _unsupported('expand');
+  T firstWhere(bool f(T e), {T orElse()}) => _unsupported('firstWhere');
+  fold(initialValue, combine(value, T element)) => _unsupported('fold');
+  T get last => _unsupported('get:last');
+  T lastWhere(bool f(T e), {T orElse()}) => _unsupported('lastWhere');
+  String join([separator = '']) => _unsupported('join');
+  T reduce(T combine(T a, T b)) => _unsupported('reduce');
+  T singleWhere(bool f(T e)) => _unsupported('singleWhere');
+  Iterable<T> skipWhile(bool f(T e)) => _unsupported('skipWhile');
+  Iterable<T> take(int n) => _unsupported('take');
+  Iterable<T> takeWhile(bool f(T e)) => _unsupported('takeWhile');
+  Set<T> toSet() => _unsupported('toSet');
+  Iterable<T> where(bool f(T e)) => _unsupported('where');
+
+  _unsupported(String method) => throw new UnsupportedError(method);
 }
 
 /// Builder object for creating linked lists using [Link] or fixed-length [List]
 /// objects.
 abstract class LinkBuilder<T> {
   factory LinkBuilder() = LinkBuilderImplementation;
 
   /// Prepends all elements added to the builder to [tail]. The resulting list
   /// is returned and the builder is cleared.
   Link<T> toLink([Link<T> tail = const Link()]);
@@ skipping 10 matching lines @@
 
   /// Returns the number of elements in the list being built.
   final int length;
 
   /// Returns `true` if the list being built is empty.
   final bool isEmpty;
 
   /// Removes all added elements and resets the builder.
   void clear();
 }