[regexp] restrict pattern syntax for unicode mode.

test/mjsunit/harmony/unicode-regexp-restricted-syntax.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: --harmony-unicode-regexps
+
+// test262/data/test/language/literals/regexp/u-dec-esc
+assertThrows("/\\1/u");
+// test262/language/literals/regexp/u-invalid-char-range-a
+assertThrows("/[\\w-a]/u");
+// test262/language/literals/regexp/u-invalid-char-range-b
+assertThrows("/[a-\\w]/u");
+// test262/language/literals/regexp/u-invalid-char-esc
+assertThrows("/\\c/u");
+assertThrows("/\\c0/u");
+// test262/built-ins/RegExp/unicode_restricted_quantifiable_assertion
+assertThrows("/(?=.)*/u");
+// test262/built-ins/RegExp/unicode_restricted_octal_escape
+assertThrows("/[\\1]/u");
+assertThrows("/\\00/u");
+assertThrows("/\\09/u");
+// test262/built-ins/RegExp/unicode_restricted_identity_escape_alpha
+assertThrows("/[\\c]/u");
+// test262/built-ins/RegExp/unicode_restricted_identity_escape_c
+assertThrows("/[\\c0]/u");
+// test262/built-ins/RegExp/unicode_restricted_incomple_quantifier
+assertThrows("/a{/u");
+assertThrows("/a{1,/u");
+assertThrows("/{/u");
+assertThrows("/}/u");
+// test262/data/test/built-ins/RegExp/unicode_restricted_brackets
+assertThrows("/]/u");
+// test262/built-ins/RegExp/unicode_identity_escape
+/\//u;