[crankshaft] Ensure that we use inlined Array.prototype.shift only when there's no elements in the …

test/mjsunit/regress/regress-crbug-663340.js

+// 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
+
+var expected = undefined;
+
+function foo() {
+  var a = [0,,{}];
+  a.shift();
+  assertEquals(expected, a[0]);
+}
+foo();
+foo();
+%OptimizeFunctionOnNextCall(foo);
+foo();
+
+expected = 42;
+Array.prototype[0] = 153;
+Array.prototype[1] = expected;
+foo();
+
+function bar() {
+  var a = [0,,{}];
+  a.shift();
+  assertEquals(expected, a[0]);
+}
+bar();
+bar();
+%OptimizeFunctionOnNextCall(bar);
+bar();