Revert "Change dart:io Platform.script to return a Uri."

tests/standalone/io/secure_socket_test.dart

 // Copyright (c) 2013, 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
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 import "package:expect/expect.dart";
@@ skipping 16 matching lines @@
             request.response.add([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
           }
           request.response.close();
         });
     });
     return server;
   });
 }
 
 void InitializeSSL() {
-  var testPkcertDatabase = Platform.script.resolve('pkcert').toFilePath();
+  var testPkcertDatabase = join(dirname(Platform.script), 'pkcert');
   SecureSocket.initialize(database: testPkcertDatabase,
                           password: 'dartdart');
 }
 
 void main() {
   InitializeSSL();
   List<int> body = <int>[];
   startServer().then((server) {
     SecureSocket.connect("localhost", server.port).then((socket) {
       socket.write("GET / HTTP/1.0\r\nHost: localhost\r\n\r\n");
@@ skipping 10 matching lines @@
         },
         onError: (e) {
           String msg = "Unexpected error $e";
           var trace = getAttachedStackTrace(e);
           if (trace != null) msg += "\nStackTrace: $trace";
           Expect.fail(msg);
         });
     });
   });
 }