Generate prettier loops.

frog/tests/leg/src/mock_compiler.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.
 
 #library('mock_compiler');
 
 #import("../../../../lib/uri/uri.dart");
 
 #import("../../../leg/elements/elements.dart");
 #import("../../../leg/io/io.dart", prefix: 'io');
@@ skipping 18 matching lines @@
   guard$array(x) { return x; }
   guard$num(x) { return x; }
   guard$string(x) { return x; }
   guard$stringOrArray(x) { return x; }
   builtin$add$1(receiver, value) {}
   builtin$get$length(var receiver) {}
   builtin$filter$1(receiver, predicate) {}
   builtin$removeLast$0(receiver) {}
   index(a, index) {}
   indexSet(a, index, value) {}
-  class Closure {} ''';
+  class Closure {}
+  builtin$iterator$0() {}
+  builtin$next$0() {}
+  builtin$hasNext$0() {}''';
 
 final String DEFAULT_CORELIB = @'''
   print(var obj) {}
   class int {}
   class double {}
   class bool {}
   class String {}
   class Object {}''';
 
 class MockCompiler extends Compiler {
@@ skipping 135 matching lines @@
   importLibrary(library, compiler.coreLibrary, compiler);
   return library;
 }
 
 class StringScript extends Script {
   final String code;
   StringScript(this.code) : super(null, null);
   String get text() => code;
   String get name() => "mock script";
 }