Change dart:io Platform.script to return a URI. Change all uses of Platform.script to work with th…

tests/standalone/io/https_client_certificate_test.dart

Index: tests/standalone/io/https_client_certificate_test.dart
diff --git a/tests/standalone/io/https_client_certificate_test.dart b/tests/standalone/io/https_client_certificate_test.dart
index 7000169c5adf98c9bf6d77faab24c6d86db3e860..f63d383cc0ebf5c6857d133f0ff93ebc1f8d8126 100644
--- a/tests/standalone/io/https_client_certificate_test.dart
+++ b/tests/standalone/io/https_client_certificate_test.dart
@@ -46,7 +46,7 @@ Function test() {
 }
 
 void InitializeSSL() {
-  var testPkcertDatabase = join(dirname(Platform.script), 'pkcert');
+  var testPkcertDatabase = Platform.script.resolve('pkcert').toFilePath();
   SecureSocket.initialize(database: testPkcertDatabase,
                           password: 'dartdart');
 }