Handle @proxy classes in type checker.

tests/language/proxy_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 for static warnings for member access on classes with @proxy annotation.
+
+class NonProxy {}
+
+@proxy
+class Proxy {}
+
+const alias = proxy;
+
+@alias
+class AliasProxy {}
+
+main() {
+  try { new NonProxy().foo; } catch (e) {} /// 01: static type warning
+  try { new NonProxy().foo(); } catch (e) {} /// 02: static type warning
+
+  try { new Proxy().foo; } catch (e) {} /// 03: ok
+  try { new Proxy().foo(); } catch (e) {} /// 04: ok
+
+  try { new AliasProxy().foo; } catch (e) {} /// 05: ok
+  try { new AliasProxy().foo(); } catch (e) {} /// 06: ok
+}