Fix checks to bit flags of PreParserExpression

test/mjsunit/regress-3456.js

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --min-preparse-length 1
+
+// Arrow function parsing (commit r22366) changed the flags stored in
+// PreParserExpression, and IsValidReferenceExpression() would return
+// false for certain valid expressions. This case is the minimum amount
+// of code needed to validate that IsValidReferenceExpression() works
+// properly. If it does not, a ReferenceError is thrown during parsing.
+
+function f() { ++(this.foo) }