Store subtyped names in Analysis Driver unlinked units.

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 0f280e6d1bcca09cf577bf869ac6300c42a76c30..6ba07b2120aba6b8133f62132d4af92e069658a2 100644
--- a/pkg/analyzer/test/src/dart/analysis/file_state_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/file_state_test.dart
@@ -673,6 +673,19 @@ class C {
     expect(file.apiSignature, signature);
   }
 
+  test_subtypedNames() {
+    String path = _p('/test.dart');
+    provider.newFile(
+        path,
+        r'''
+class X extends A {}
+class Y extends A with B {}
+class Z implements C, D {}
+''');
+    FileState file = fileSystemState.getFileForPath(path);
+    expect(file.referencedNames, unorderedEquals(['A', 'B', 'C', 'D']));
+  }
+
   test_topLevelDeclarations() {
     String path = _p('/aaa/lib/a.dart');
     provider.newFile(