Do not do global optimizations on fields and parameters when invokeOn is enabled.

tests/compiler/dart2js_extra/no_such_method_mirrors_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.
+
+import 'dart:mirrors';
+import 'package:expect/expect.dart';
+
+class A {
+  noSuchMethod(im) {
+    reflect(new B()).delegate(im);
+  }
+}
+
+class B {}
+
+main() {
+  // Test with an intercepted selector.
+  Expect.throws(() => new A().startsWith(42), (e) => e is NoSuchMethodError);
+  // Test with a non-intercepted selector.
+  Expect.throws(() => new A().foobar(), (e) => e is NoSuchMethodError);
+}