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

tests/standalone/io/process_sync_test.dart

Index: tests/standalone/io/process_sync_test.dart
diff --git a/tests/standalone/io/process_sync_test.dart b/tests/standalone/io/process_sync_test.dart
index 55af8314591b836833f30446f7e149044c2b44c4..7601ddf742fff6c2bf9cb43f59f914e04987c66e 100644
--- a/tests/standalone/io/process_sync_test.dart
+++ b/tests/standalone/io/process_sync_test.dart
@@ -12,8 +12,9 @@ test(int blockCount,
      int exitCode,
      [int nonWindowsExitCode]) {
   // Get the Dart script file that generates output.
-  var scriptFile = new File(join(dirname(Platform.script),
-                                 "process_sync_script.dart"));
+  var scriptFile = new File(Platform.script
+                                    .resolve("process_sync_script.dart")
+                                    .toFilePath());
   var args = [scriptFile.path,
               blockCount.toString(),
               stdoutBlockSize.toString(),