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

tests/standalone/io/file_read_special_device_test.dart

Index: tests/standalone/io/file_read_special_device_test.dart
diff --git a/tests/standalone/io/file_read_special_device_test.dart b/tests/standalone/io/file_read_special_device_test.dart
index a0455108e5396e7fe09c651d42b15ecd0162e93b..482ac573488e3a2dc6363a0010693e058e42df92 100644
--- a/tests/standalone/io/file_read_special_device_test.dart
+++ b/tests/standalone/io/file_read_special_device_test.dart
@@ -7,7 +7,7 @@ import 'package:path/path.dart';
 import 'dart:io';
 
 void openAndWriteScript(String script) {
-  script = join(dirname(Platform.script), script);
+  script = Platform.script.resolve(script).toFilePath();
   var executable = Platform.executable;
   var file = script;  // Use script as file.
   Process.start("bash", ["-c", "$executable $script < $file"]).then((process) {