Fix checked mode test

tests/standalone/io/platform_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.
 
 import "dart:async";
 import "dart:io";
 import "dart:isolate";
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
@@ skipping 50 matching lines @@
     Expect.isTrue(uri.path.endsWith('tests/standalone/io/platform_test.dart'));
     Expect.equals(Platform.packageRoot, results["Platform.packageRoot"]);
     Expect.listEquals(Platform.executableArguments,
                       results["Platform.executableArguments"]);
     asyncEnd();
   });
 }
 
 
 testVersion() {
-  checkValidVersion(string version) {
+  checkValidVersion(String version) {
     RegExp re = new RegExp(r'(\d+)\.(\d+)\.(\d+)(-dev\.([^\.]*)\.([^\.]*))?');
     var match = re.firstMatch(version);
     Expect.isNotNull(match);
     // Major version.
     Expect.isTrue(int.parse(match.group(1)) == 1);
     // Minor version.
     Expect.isTrue(int.parse(match.group(2)) >= 9);
     // Patch version.
     Expect.isTrue(int.parse(match.group(3)) >= 0);
     // Dev
@@ skipping 25 matching lines @@
   Expect.throws(() => checkValidVersion('x.y.z'));
 }
 
 main() {
   // This tests assumes paths relative to dart main directory
   Directory.current = Platform.script.resolve('../../..').toFilePath();
   test();
   testIsolate();
   testVersion();
 }