[turbofan] Fix representation changes for unsigned values used as checked-signed values.

test/mjsunit/compiler/regress-664117.js

Index: test/mjsunit/compiler/regress-664117.js
diff --git a/test/mjsunit/compiler/regress-664117.js b/test/mjsunit/compiler/regress-664117.js
new file mode 100644
index 0000000000000000000000000000000000000000..cf00591340db4b643d103df5a377b151e84ff342
--- /dev/null
+++ b/test/mjsunit/compiler/regress-664117.js
@@ -0,0 +1,16 @@
+// Copyright 2016 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: --allow-natives-syntax
+
+function foo() {
+  return v.length + 1;
+}
+
+var v = [];
+foo();
+v.length = 0xFFFFFFFF;
+
+%OptimizeFunctionOnNextCall(foo);
+assertEquals(4294967296, foo());