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

src/regexp/jsregexp.cc

Index: src/regexp/jsregexp.cc
diff --git a/src/regexp/jsregexp.cc b/src/regexp/jsregexp.cc
index 7b510b072b0bba0d6e66726397213c52ead70a9f..0828c6d10ad89e384b197d1a388c77d261a6188f 100644
--- a/src/regexp/jsregexp.cc
+++ b/src/regexp/jsregexp.cc
@@ -4905,7 +4905,7 @@ UnicodeRangeSplitter::UnicodeRangeSplitter(Zone* zone,
                   kLeadSurrogates, zone_);
   table_.AddRange(CharacterRange(kTrailSurrogateStart, kTrailSurrogateEnd),
                   kTrailSurrogates, zone_);
-  table_.AddRange(CharacterRange(kTrailSurrogateEnd, kNonBmpStart - 1),
+  table_.AddRange(CharacterRange(kTrailSurrogateEnd + 1, kNonBmpStart - 1),
                   kBmpCodePoints, zone_);
   table_.AddRange(CharacterRange(kNonBmpStart, kNonBmpEnd), kNonBmpCodePoints,
                   zone_);