Revert of Put RegExp js code in strict mode (patchset #2 id:20001 of https://codereview.chromium.or…

test/mjsunit/regexp-lastIndex.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.
-
-// lastIndex is set according to funny rules. It is typically set only
-// for global or sticky RegExps, but on a failure to find a match, it is
-// set unconditionally. If a set fails, then it acts as if in strict mode
-// and throws.
-
-var re = /x/;
-Object.defineProperty(re, 'lastIndex', {writable: false});
-assertThrows(() => re.exec(""), TypeError);
-assertEquals(["x"], re.exec("x"));
-
-var re = /x/y;
-Object.defineProperty(re, 'lastIndex', {writable: false});
-assertThrows(() => re.exec(""), TypeError);
-assertThrows(() => re.exec("x"), TypeError);