Revert of [regexp] restrict pattern syntax for unicode mode. (patchset #6...

Revert of [regexp] restrict pattern syntax for unicode mode. (patchset #6 id:120001 of https://codereview.chromium.org/1645573002/ )

Reason for revert:
[Sheriff] Breaks layout tests:
https://build.chromium.org/p/client.v8.fyi/builders/V8-Blink%20Linux%2064/builds/4222

Original issue's description:
> [regexp] restrict pattern syntax for unicode mode.
>
> ES2015 Annex B.1.4 specifies a restricted pattern language for unicode
> mode. This change reflects that, based on some test262 test cases.
>
> R=littledan@chromium.org
> BUG=v8:2952
> LOG=N
>
> Committed: https://crrev.com/e918c4ec464456a374098049ca22eac2107f6223
> Cr-Commit-Position: refs/heads/master@{#33584}

TBR=vogelheim@chromium.org,yangguo@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:2952

Review URL: https://codereview.chromium.org/1648673002

Cr-Commit-Position: refs/heads/master@{#33588}

src/regexp/regexp-parser.h

@@ -111,7 +111,7 @@ class RegExpBuilder : public ZoneObject {
   void AddTerm(RegExpTree* tree);
   void AddAssertion(RegExpTree* tree);
   void NewAlternative();  // '|'
-  bool AddQuantifierToAtom(int min, int max,
+  void AddQuantifierToAtom(int min, int max,
                            RegExpQuantifier::QuantifierType type);
   RegExpTree* ToRegExp();
 
@@ -198,7 +198,7 @@ class RegExpParser BASE_EMBEDDED {
   bool unicode() const { return (flags_ & JSRegExp::kUnicode) != 0; }
   bool multiline() const { return (flags_ & JSRegExp::kMultiline) != 0; }
 
-  static bool IsSyntaxCharacterOrSlash(uc32 c);
+  static bool IsSyntaxCharacter(uc32 c);
 
   static const int kMaxCaptures = 1 << 16;
   static const uc32 kEndMarker = (1 << 21);

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;