Adding Lasse's improvement to r4364 ...

src/regexp.js

 // Copyright 2006-2009 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 148 matching lines @@
 
   if (%_ObjectEquals(cache.type, 'exec') &&
       %_ObjectEquals(cache.lastIndex, this.lastIndex) &&
       %_ObjectEquals(cache.regExp, this) &&
       %_ObjectEquals(cache.subject, string)) {
     if (cache.answerSaved) {
       return CloneRegexpAnswer(cache.answer);
     } else {
       saveAnswer = true;
     }
-  } else {
-    cache.answerSaved = false;
   }
 
   if (%_ArgumentsLength() == 0) {
     var regExpInput = LAST_INPUT(lastMatchInfo);
     if (IS_UNDEFINED(regExpInput)) {
       throw MakeError('no_input_to_regexp', [this]);
     }
     string = regExpInput;
   }
   var s;
@@ skipping 48 matching lines @@
   }
 
   result.index = lastMatchInfo[CAPTURE0];
   result.input = s;
   if (this.global) {
     this.lastIndex = lastMatchInfo[CAPTURE1];
   } else {
     cache.regExp = this;
     cache.subject = s;
     cache.lastIndex = lastIndex;
-    if (saveAnswer) {
-      cache.answer = CloneRegexpAnswer(result);
-      cache.answerSaved = true;
-    }
+    if (saveAnswer) cache.answer = CloneRegexpAnswer(result);
+    cache.answerSaved = saveAnswer;
     cache.type = 'exec';
   }
   return result;
 
 }
 
 
 // Section 15.10.6.3 doesn't actually make sense, but the intention seems to be
 // that test is defined in terms of String.prototype.exec. However, it probably
 // means the original value of String.prototype.exec, which is what everybody
@@ skipping 254 matching lines @@
   %DefineAccessor($RegExp, "$'", SETTER, NoOpSetter, DONT_ENUM | DONT_DELETE);
 
   for (var i = 1; i < 10; ++i) {
     %DefineAccessor($RegExp, '$' + i, GETTER, RegExpMakeCaptureGetter(i), DONT_DELETE);
     %DefineAccessor($RegExp, '$' + i, SETTER, NoOpSetter, DONT_DELETE);
   }
 }
 
 
 SetupRegExp();