* Fixed bug in handling of quantified look-aheads.

src/jsregexp.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 253 matching lines @@
     FlatStringReader reader(pattern);
     if (!ParseRegExp(&reader, flags.is_multiline(), &parse_result)) {
       // Throw an exception if we fail to parse the pattern.
       ThrowRegExpException(re,
                            pattern,
                            parse_result.error,
                            "malformed_regexp");
       return Handle<Object>::null();
     }
     RegExpAtom* atom = parse_result.tree->AsAtom();
-    if (atom != NULL && !flags.is_ignore_case()) {
-      if (parse_result.has_character_escapes) {
+    if (atom != NULL &&
+        !flags.is_ignore_case() &&
+        parse_result.capture_count == 0) {
+      if (parse_result.non_simple) {
         Vector<const uc16> atom_pattern = atom->data();
         Handle<String> atom_string =
             Factory::NewStringFromTwoByte(atom_pattern);
         result = AtomCompile(re, pattern, flags, atom_string);
       } else {
         result = AtomCompile(re, pattern, flags, pattern);
       }
     } else {
       if (FLAG_irregexp) {
         result = IrregexpPrepare(re, pattern, flags);
@@ skipping 3545 matching lines @@
   EmbeddedVector<byte, 1024> codes;
   RegExpMacroAssemblerIrregexp macro_assembler(codes);
   return compiler.Assemble(&macro_assembler,
                            node,
                            data->capture_count,
                            pattern);
 }
 
 
 }}  // namespace v8::internal