// This is the size needed to add the replacement, not the full size
      // needed by the string. We only regrow when we absolutely must, and
      // when we do grow, grow enough to avoid excessive growing. Grow.
      int sizeNeeded = destIndex + charsSkipped + rlen;
      if (destSize < sizeNeeded) {
        destSize = sizeNeeded + DEST_PAD_MULTIPLIER * (slen - index);
        dest = growBuffer(dest, destIndex, destSize);