Fix spread operator in ArrayLiterals when nested in other literals

test/mjsunit/harmony/regress/regress-4417.js

+// Copyright 2015 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: --harmony-spread-arrays
+
+var arr = [1, 2, 3];
+assertEquals({arr: [1, 2, 3]}, {arr: [...arr]});
+assertEquals([[1, 2, 3]], [[...arr]]);
+
+assertEquals({arr: [6, 5, [1, 2, 3]]}, {arr: [6, 5, [...arr]]});
+assertEquals([8, 7, [6, 5, [1, 2, 3]]], [8, 7, [6, 5, [...arr]]]);