Remove backwards compatibility 'win32' name from test status files.

tools/testing/dart/test_options.dart

Index: tools/testing/dart/test_options.dart
diff --git a/tools/testing/dart/test_options.dart b/tools/testing/dart/test_options.dart
index df25505cb034336c8994de8d963763c54cb643e5..35f5b3e2aaa7da782a645cd29f9f0414f4f1474d 100644
--- a/tools/testing/dart/test_options.dart
+++ b/tools/testing/dart/test_options.dart
@@ -358,14 +358,6 @@ Controls how dart code is compiled and executed.
    * into a list of configurations with exactly one value per key.
    */
   List<Map> _expandConfigurations(Map configuration) {
-
-    // TODO(ager): Get rid of this. This is for backwards
-    // compatibility with the python test scripts. They use system
-    // 'win32' for Windows.
-    if (configuration['system'] == 'windows') {
-      configuration['system'] = 'win32';
-    }
-
     // Expand the pseudo-values such as 'all'.
     if (configuration['arch'] == 'all') {
       configuration['arch'] = 'ia32,x64';