Missed one path when fixing Window bots (TBR)

pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart

Index: pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart
diff --git a/pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart b/pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart
index 9fad1b6bb2cda7f1c113b522c413e0c906767115..06da87cba3187784c6e410a02e0ce74e0d05646e 100644
--- a/pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart
+++ b/pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart
@@ -59,7 +59,7 @@ abstract class BuilderTestMixin {
 @reflectiveTest
 class DartChangeBuilderImplTest extends AbstractContextTest {
   test_createFileEditBuilder() async {
-    String path = '/test.dart';
+    String path = provider.convertPath('/test.dart');
     addSource(path, 'library test;');
     int timeStamp = 54;
     DartChangeBuilderImpl builder = new DartChangeBuilderImpl(driver);