Use AnalysisDriverUnlinkedUnit as a container for UnlinkedUnit and referenced names.

pkg/analyzer/test/src/dart/analysis/file_state_test.dart

Index: pkg/analyzer/test/src/dart/analysis/file_state_test.dart
diff --git a/pkg/analyzer/test/src/dart/analysis/file_state_test.dart b/pkg/analyzer/test/src/dart/analysis/file_state_test.dart
index 2ef6802a9a377c2fa11af4a92520a7b7e48065b2..60b4622dce65d022e760a6bba552addba8933bf3 100644
--- a/pkg/analyzer/test/src/dart/analysis/file_state_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/file_state_test.dart
@@ -211,6 +211,21 @@ part 'not-a2.dart';
     expect(files, [filePackageUri, fileFileUri]);
   }
 
+  test_referencedNames() {
+    String path = _p('/aaa/lib/a.dart');
+    provider.newFile(
+        path,
+        r'''
+A foo(B p) {
+  foo(null);
+  C c = new C(p);
+  return c;
+}
+''');
+    FileState file = fileSystemState.getFileForPath(path);
+    expect(file.referencedNames, unorderedEquals(['A', 'B', 'C']));
+  }
+
   test_refresh_differentApiSignature() {
     String path = _p('/aaa/lib/a.dart');
     provider.newFile(