[Intl] Fix /ſ/i.test('ſ'.toUpperCase()) be false.

Address special case condiction for U+017F.

Bug: v8:9356
Change-Id: Id24e5e2c999b198bf0f696aea8c98f223508c051
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1827683
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64028}

src/regexp/regexp-compiler.cc

@@ -725,6 +725,11 @@ static int GetCaseIndependentLetters(Isolate* isolate, uc16 character,
                                      unibrow::uchar* letters,
                                      int letter_length) {
 #ifdef V8_INTL_SUPPORT
+  // Special case for U+017F which has upper case in ASCII range.
+  if (character == 0x017f) {
+    letters[0] = character;
+    return 1;
+  }
   icu::UnicodeSet set;
   set.add(character);
   set = set.closeOver(USET_CASE_INSENSITIVE);

test/intl/regress-9356.js

+// Copyright 2019 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.
+
+assertFalse(/ſ/i.test('ſ'.toUpperCase()));
+assertFalse(/ſ/i.test('ſ'.toUpperCase()[0]));
+assertTrue(/ſ/i.test('ſ'));
+assertTrue(/ſ/i.test('ſ'[0]));
+assertFalse(/ſ/i.test('s'.toUpperCase()));
+assertFalse(/ſ/i.test('s'.toUpperCase()[0]));
+assertFalse(/ſ/i.test('S'.toUpperCase()));
+assertFalse(/ſ/i.test('S'.toUpperCase()[0]));
+assertFalse(/ſ/i.test('S'));
+assertFalse(/ſ/i.test('S'[0]));