Fix a bug in the type inferrer, where a getter call was not seen as a potential closure call.

tests/language/inferrer_closure_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.
+
+// Regression test for dart2js that used to not see a closure could be
+// invoked through a getter access followed by an invocation.
+
+var closure = (a) => a.toString();
+
+get foo => closure;
+
+main() {
+  if (foo(42) != '42') {
+    throw 'Test failed';
+  }
+}