Parse parenthesized expressions.

dart/frog/leg/typechecker.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.
 
 class TypeCheckerTask extends CompilerTask {
   TypeCheckerTask(Compiler compiler) : types = new Types(), super(compiler);
   String get name() => "Type checker";
   Types types;
 
   void check(Node tree, Map<Node, Element> elements) {
@@ skipping 367 matching lines @@
         checkAssignable(node, type, initializer);
       }
     }
     return null;
   }
 
   Type visitWhile(While node) {
     checkCondition(node.condition);
     type(node.body);
   }
+
+  Type visitParenthesizedExpression(ParenthesizedExpression node) {
+    return type(node.expression);
+  }
 }