Throw when reflecting on elements not covered by a `MirrorsUsed` annotation.

tests/compiler/dart2js_extra/mirror_invalid_invoke_test.dart

+// Copyright (c) 2013, 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.
+
+// Test that we cannot reflect on elements not covered by the `MirrorsUsed`
+// annotation.
+
+library test;
+
+@MirrorsUsed(targets: 'foo')
+import 'dart:mirrors';
+
+import 'package:expect/expect.dart';
+
+import '../../language/compiler_annotations.dart';
+
+foo() => 1;
+
+@DontInline
+// Use a closure to prevent inlining until the annotation is implemented.
+bar() => () => 2;
+
+main() {
+  bar();  // Call bar, so it is included in the program.
+
+  var lm = currentMirrorSystem().findLibrary(const Symbol('test')).single;
+  Expect.equals(1, lm.invoke(const Symbol('foo'), []).reflectee);
+  Expect.throws(() => lm.invoke(const Symbol('bar'),  []));
+}