Implement parsing and resolving of type-variables.

frog/leg/tree/unparser.dart

-// 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.
 
 class Unparser implements Visitor {
   StringBuffer sb;
   final bool printDebugInfo;
 
   Unparser([this.printDebugInfo = false]);
 
   String unparse(Node node) {
@@ skipping 193 matching lines @@
       sb.add(' ');
       visit(node.expression);
     }
     node.endToken.value.printOn(sb);
   }
 
   visitTypeAnnotation(TypeAnnotation node) {
     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);
     } else {
       sb.add('var');
     }
     sb.add(' ');
     // TODO(karlklose): print modifiers.
     visit(node.definitions);
     if (node.endToken.value == const SourceString(';')) {
@@ skipping 162 matching lines @@
       sb.add(' ');
     }
     visit(node.name);
     if (node.typeParameters !== null) {
       visit(node.typeParameters);
     }
     visit(node.formals);
     add(node.endToken.value);
   }
 }