Implement parsing and resolving of type-variables.

frog/leg/tree/unparser.dart

Index: frog/leg/tree/unparser.dart
diff --git a/frog/leg/tree/unparser.dart b/frog/leg/tree/unparser.dart
index d4b12f148705a2cc0a9eca1e983088fcc518a6ab..803d68074b0cd0e722fe215b3c72104ba13ddb17 100644
--- a/frog/leg/tree/unparser.dart
+++ b/frog/leg/tree/unparser.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
@@ -212,6 +212,14 @@ class Unparser implements Visitor {
     node.visitChildren(this);
   }
 
+  visitTypeVariable(TypeVariable node) {
+    visit(node.name);
+    if (node.bound !== null) {
+      sb.add(' extends ');
+      visit(node.bound);
+    }
+  }
+
   visitVariableDefinitions(VariableDefinitions node) {
     if (node.type !== null) {
       visit(node.type);