[regexp, intl] Intl should not cause side effects to the RegExp object.

test/intl/regexp-assert.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.
+
+assertEquals("a", RegExp.$1);
+assertEquals("b", RegExp.$2);
+assertEquals("c", RegExp.$3);
+assertEquals("d", RegExp.$4);
+assertEquals("e", RegExp.$5);
+assertEquals("f", RegExp.$6);
+assertEquals("g", RegExp.$7);
+assertEquals("h", RegExp.$8);
+assertEquals("i", RegExp.$9);
+
+assertEquals("abcdefghij", RegExp.lastMatch);
+assertEquals("j", RegExp.lastParen);
+assertEquals(">>>", RegExp.leftContext);
+assertEquals("<<<", RegExp.rightContext);
+assertEquals(">>>abcdefghij<<<", RegExp.input);