Make sure to visit function annotations in ElementBuilder.

tests/language/instance_creation_in_function_annotation_test.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Verify that instance creation expressions inside function
+// annotations are properly handled.  See dartbug.com/23354
+
+import 'dart:mirrors';
+import 'package:expect/expect.dart';
+
+class C {
+  final String s;
+  const C(this.s);
+}
+
+class D {
+  final C c;
+  const D(this.c);
+}
+
+@D(const C('foo'))
+f() {}
+
+main() {
+  ClosureMirror closureMirror = reflect(f);
+  List<InstanceMirror> metadata = closureMirror.function.metadata;
+  Expect.equals(1, metadata.length);
+  Expect.equals(metadata[0].reflectee.c.s, 'foo');
+}