Compute frontend/backend specific constants.

tests/language/proxy3_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.
+
+const isFalse = identical(-0.0, 0);
+
+const validProxy = isFalse ? null : proxy;
+const invalidProxy = isFalse ? proxy : null;
+
+@validProxy
+class ValidProxy {}
+
+@invalidProxy
+class InvalidProxy {}
+
+main() {
+  try { new InvalidProxy().foo; } catch (e) {}  /// 01: static type warning
+  try { new InvalidProxy().foo(); } catch (e) {}  /// 02: static type warning
+
+  try { new ValidProxy().foo; } catch (e) {} /// 03: ok
+  try { new ValidProxy().foo(); } catch (e) {} /// 04: ok
+}