[regexp] fix off-by-one in UnicodeRangeSplitter.

test/mjsunit/harmony/unicode-character-ranges.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 --harmony-regexp-lookbehind
 
 function execl(expectation, regexp, subject) {
   if (regexp instanceof String) regexp = new RegExp(regexp, "u");
   assertEquals(expectation, regexp.exec(subject));
 }
@@ skipping 78 matching lines @@
 
 execl(["\ud800X"], /.X/u, "\ud800XaX");
 execl(["aX"], /.(?<!\ud800)X/u, "\ud800XaX");
 execl(["aX"], /.(?<![\ud800-\ud900])X/u, "\ud800XaX");
 
 execl(null, /[]/u, "\u1234");
 execl(["0abc"], /[^]abc/u, "0abc");
 execl(["\u1234abc"], /[^]abc/u, "\u1234abc");
 execl(["\u{12345}abc"], /[^]abc/u, "\u{12345}abc");
 
+execl(null, /[\u{0}-\u{1F444}]/u, "\ud83d\udfff");
+
 // Backward matches of lone surrogates.
 execl(["B", "\ud803A"], /(?<=([\ud800-\ud900]A))B/u,
       "\ud801\udc00AB\udc00AB\ud802\ud803AB");
 execl(["B", "\udc00A"], /(?<=([\ud800-\u{10300}]A))B/u,
        "\ud801\udc00AB\udc00AB\ud802\ud803AB");
 execl(["B", "\udc11A"], /(?<=([\udc00-\udd00]A))B/u,
       "\ud801\udc00AB\udc11AB\ud802\ud803AB");
 execl(["X", "\ud800C"], /(?<=(\ud800\w))X/u,
       "\ud800\udc00AX\udc11BX\ud800\ud800CX");
 execl(["C", "\ud800\ud800"], /(?<=(\ud800.))\w/u,
@@ skipping 38 matching lines @@
 tests(true, "...(?<=" + L + ")", X + T + L);
 tests(false, "...(?<=" + T + ")", X + L + T)
 tests(true, "..(?<=" + L + T + ")", X + L + T)
 tests(true, "..(?<=" + L + T + "(?<=" + L + T + "))", X + L + T);
 tests(false, "..(?<=" + L + "(" + T + "))", X + L + T);
 tests(false, ".*" + L, X + L + T);
 tests(true, ".*" + L, X + L + L + T);
 tests(false, ".*" + L, X + L + T + L + T);
 tests(false, ".*" + T, X + L + T + L + T);
 tests(true, ".*" + T, X + L + T + T + L + T);