nsWritingIterator<CharT> result; return BeginWriting(result);
aResult.mOwningString = this; GetWritableFragment(aResult.mFragment, kFirstFragment); aResult.mPosition = aResult.mFragment.mStart; aResult.normalize_forward(); return aResult;
      BeginWriting()        {          nsWritingIterator<CharT> result;          return BeginWriting(result); // copies (since I return a value, not a reference)        }