Make String.charCodes a getter.

tests/standalone/io/http_server_early_client_close_test.dart

 #import("dart:io");
 #import("dart:isolate");
 
 void sendData(List<int> data, int port) {
   Socket socket = new Socket("127.0.0.1", port);
   socket.onConnect = () {
     socket.onData = () {
       Expect.fail("No data response was expected");
     };
     socket.outputStream.onNoPendingWrites = () {
@@ skipping 25 matching lines @@
       Expect.isFalse(calledOnError);
       Expect.equals(exception, error.message);
       Expect.equals(expectRequest, calledOnRequest);
       calledOnError = true;
       port.close();
       c.complete(null);
     };
 
     List<int> d;
     if (data is List<int>) d = data;
-    if (data is String) d = data.charCodes();
+    if (data is String) d = data.charCodes;
     if (d == null) Expect.fail("Invalid data");
     sendData(d, server.port);
 
     return c.future;
   }
 
   final data;
   final String exception;
   final bool expectRequest;
 }
@@ skipping 28 matching lines @@
     } else {
       server.close();
     }
   }
   runTest(tests.iterator());
 }
 
 void main() {
   testEarlyClose();
 }