Ensure metadata on imports/exports is resolved for serialization.

tests/compiler/dart2js/serialization/test_data.dart

Index: tests/compiler/dart2js/serialization/test_data.dart
diff --git a/tests/compiler/dart2js/serialization/test_data.dart b/tests/compiler/dart2js/serialization/test_data.dart
index 04f8fd1eb6694921081c7591bb9116cb5e36fca7..bf8ecf8330739ef172d0f0389aacefb3bbe94879 100644
--- a/tests/compiler/dart2js/serialization/test_data.dart
+++ b/tests/compiler/dart2js/serialization/test_data.dart
@@ -699,6 +699,24 @@ main() => a;
     'main.dart': '''
 main() => new Null();
 '''}),
+
+  const Test('Metadata on imports', const {},
+      preserializedSourceFiles: const {
+        'main.dart': '''
+@deprecated
+import 'main.dart';
+
+main() {}
+'''}),
+
+  const Test('Metadata on exports', const {},
+      preserializedSourceFiles: const {
+        'main.dart': '''
+@deprecated
+export 'main.dart';
+
+main() {}
+'''}),
 ];
 
 class Test {