Update library syntax in pkg files.

pkg/htmlescape/lib/htmlescape.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.
 
 /**
  * This library contains functions to escape strings for safe inclusion
  * in HTML source.
  */
-#library("htmlescape");
+library htmlescape;
 
 /**
  * Escapes HTML-special characters of [text] so that the result can be
  * included verbatim in HTML source code, either in an element body or in an
  * attribute value.
  */
 String htmlEscape(String text) {
   // TODO(efortuna): A more efficient implementation.
   return text.replaceAll("&", "&")
              .replaceAll("<", "&lt;")
              .replaceAll(">", "&gt;")
              .replaceAll('"', "&quot;")
              .replaceAll("'", "&apos;");
 }