[regexp] fix /ui regexp desugaring for text nodes.

src/regexp/regexp-parser.cc

Index: src/regexp/regexp-parser.cc
diff --git a/src/regexp/regexp-parser.cc b/src/regexp/regexp-parser.cc
index 0481c838c6f1781cee66bd45064a3fa64b5a67e4..abb644ac3f8057c91c5648177b6b8bdc4d4e3f14 100644
--- a/src/regexp/regexp-parser.cc
+++ b/src/regexp/regexp-parser.cc
@@ -1473,14 +1473,10 @@ void RegExpBuilder::FlushTerms() {
 
 bool RegExpBuilder::NeedsDesugaringForUnicode(RegExpCharacterClass* cc) {
   if (!unicode()) return false;
-  switch (cc->standard_type()) {
-    case 's':        // white space
-    case 'w':        // ASCII word character
-    case 'd':        // ASCII digit
-      return false;  // These characters do not need desugaring.
-    default:
-      break;
-  }
+  // TODO(yangguo): we could be smarter than this. Case-insensitivity does not
+  // necessarily mean that we need to desugar. It's probably nicer to have a
+  // separate pass to figure out unicode desugarings.
+  if (ignore_case()) return true;
   ZoneList<CharacterRange>* ranges = cc->ranges(zone());
   CharacterRange::Canonicalize(ranges);
   for (int i = ranges->length() - 1; i >= 0; i--) {