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

tests/standalone/io/test_runner_test.dart

Index: tests/standalone/io/test_runner_test.dart
diff --git a/tests/standalone/io/test_runner_test.dart b/tests/standalone/io/test_runner_test.dart
index 86e48420c081c343a5065cc87215ee0c901a3d1e..5b540af6d1e7938d9040fd94fac5f288b78e80b4 100644
--- a/tests/standalone/io/test_runner_test.dart
+++ b/tests/standalone/io/test_runner_test.dart
@@ -83,7 +83,7 @@ class CustomTestSuite extends TestSuite {
 
   TestCase _makeNormalTestCase(name, expectations) {
     var command = CommandBuilder.instance.getCommand(
-        'custom', Platform.executable, [Platform.script, name],
+        'custom', Platform.executable, [Platform.script.toFilePath(), name],
         'ReleaseIA32');
     return _makeTestCase(name, DEFAULT_TIMEOUT, command, expectations);
   }