Implement generalized function types.

pkg/compiler/lib/src/util/util.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.
 
 library dart2js.util;
 
 import 'package:front_end/src/fasta/scanner/characters.dart';
 import 'package:front_end/src/fasta/util/link.dart';
 
 export 'emptyset.dart';
@@ skipping 173 matching lines @@
       0x3fffffff;
 }
 
 String modifiersToString(
     {bool isStatic: false,
     bool isAbstract: false,
     bool isFinal: false,
     bool isVar: false,
     bool isConst: false,
     bool isFactory: false,
-    bool isExternal: false}) {
+    bool isExternal: false,
+    bool isCovariant: false}) {
   LinkBuilder<String> builder = new LinkBuilder<String>();
   if (isStatic) builder.addLast('static');
   if (isAbstract) builder.addLast('abstract');
   if (isFinal) builder.addLast('final');
   if (isVar) builder.addLast('var');
   if (isConst) builder.addLast('const');
   if (isFactory) builder.addLast('factory');
   if (isExternal) builder.addLast('external');
+  if (isCovariant) builder.addLast('covariant');
   StringBuffer buffer = new StringBuffer();
   builder.toLink().printOn(buffer, ', ');
   return buffer.toString();
 }
 
 class Pair<A, B> {
   final A a;
   final B b;
 
   Pair(this.a, this.b);
@@ skipping 28 matching lines @@
   if (usedNames.contains(suggestedName)) {
     int counter = 0;
     while (usedNames.contains(result)) {
       counter++;
       result = "$suggestedName$counter";
     }
   }
   usedNames.add(result);
   return result;
 }