Change List constructors.

tests/standalone/io/tls_socket_test.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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // The --short_socket_write option does not work with external server
 // www.google.dk.  Add this to the test when we have secure server sockets.
 // See TODO below.
 
@@ skipping 17 matching lines @@
     tls.writeList(request_bytes, 20, request_bytes.length - 20);
   };
   var useReadList;  // Mutually recursive onData callbacks.
   void useRead() {
     var data = tls.read();
     var received = new String.fromCharCodes(data);
     chunks.add(received);
     tls.onData = useReadList;
   }
   useReadList = () {
-    var buffer = new List(2000);
+    var buffer = new List.fixedLength(2000);
     int len = tls.readList(buffer, 0, 2000);
     var received = new String.fromCharCodes(buffer.getRange(0, len));
     chunks.add(received);
     tls.onData = useRead;
   };
   tls.onData = useRead;
   tls.onClosed = () {
     String fullPage = Strings.concatAll(chunks);
     Expect.isTrue(fullPage.contains('</body></html>'));
     tls.close();
   };
 }