Attempt at pre-calculating replace regexp matches.

src/jsregexp.h

Index: src/jsregexp.h
diff --git a/src/jsregexp.h b/src/jsregexp.h
index 46d53c215e043087ae7fae8f1aac81f364ddb887..de886caa484fe2d6841c73ad59946d44c572b677 100644
--- a/src/jsregexp.h
+++ b/src/jsregexp.h
@@ -145,6 +145,14 @@ class RegExpImpl {
   }
 
   // For acting on the JSRegExp data FixedArray.
+  static bool RegExpIsAtom(FixedArray* re) {
+    return re->get(JSRegExp::kTagIndex) == Smi::FromInt(JSRegExp::ATOM);
+  }
+  static int RegExpNumberOfCaptures(FixedArray* re) {
+    return (re->get(JSRegExp::kTagIndex) == Smi::FromInt(JSRegExp::ATOM))
+           ? 0
+           : IrregexpNumberOfCaptures(re);
+  }
   static int IrregexpMaxRegisterCount(FixedArray* re);
   static void SetIrregexpMaxRegisterCount(FixedArray* re, int value);
   static int IrregexpNumberOfCaptures(FixedArray* re);