Attempt to fix complex_reload_test on Windows

runtime/observatory/tests/service/complex_reload_test.dart

Index: runtime/observatory/tests/service/complex_reload_test.dart
diff --git a/runtime/observatory/tests/service/complex_reload_test.dart b/runtime/observatory/tests/service/complex_reload_test.dart
index 848a1935fe41c3d6518b3a018a315be8947ed08e..f3fd80627646fc9de84f50c461a702e4c679ef35 100644
--- a/runtime/observatory/tests/service/complex_reload_test.dart
+++ b/runtime/observatory/tests/service/complex_reload_test.dart
@@ -66,7 +66,10 @@ var tests = [
 
     // Reload to v2.
     var response = await slaveIsolate.reloadSources(
-       rootLibUri: '$directory/complex_reload/v2/main.dart',
+       rootLibUri: '$directory${Platform.pathSeparator}'
+                  'complex_reload${Platform.pathSeparator}'
+                  'v2${Platform.pathSeparator}'
+                  'main.dart',
     );
     expect(response['success'], isTrue);
 
@@ -76,7 +79,10 @@ var tests = [
 
     // Reload to v3.
     response = await slaveIsolate.reloadSources(
-      rootLibUri: '$directory/complex_reload/v3/main.dart',
+      rootLibUri: '$directory${Platform.pathSeparator}'
+                  'complex_reload${Platform.pathSeparator}'
+                  'v3${Platform.pathSeparator}'
+                  'main.dart',
     );
     expect(response['success'], isTrue);