Fix for the watcher leak.

pkg/analysis_server/test/context_manager_test.dart

Index: pkg/analysis_server/test/context_manager_test.dart
diff --git a/pkg/analysis_server/test/context_manager_test.dart b/pkg/analysis_server/test/context_manager_test.dart
index 9fad2968c9c5bbf0d432d4c67270774c1cf6ee4b..acec25c6a88dbe98ff817b7063be1ddb683d8173 100644
--- a/pkg/analysis_server/test/context_manager_test.dart
+++ b/pkg/analysis_server/test/context_manager_test.dart
@@ -1123,9 +1123,11 @@ test_pack:lib/
     resourceProvider.newFile(pubspecPath, '');
     // add one root - there is a context
     manager.setRoots(<String>[projPath], <String>[], <String, String>{});
+    expect(manager.changeSubscriptions, hasLength(1));
     expect(callbacks.currentContextPaths, hasLength(1));
     // set empty roots - no contexts
     manager.setRoots(<String>[], <String>[], <String, String>{});
+    expect(manager.changeSubscriptions, hasLength(0));
     expect(callbacks.currentContextPaths, hasLength(0));
     expect(callbacks.currentContextFilePaths, hasLength(0));
   }