nsACString::size_type src_len = aSource.Length(), sub_len = aSubstring.Length();
nsAString::size_type src_len = aSource.Length(), sub_len = aSubstring.Length();
StringEndsWith( const nsACString& aSource, const nsACString& aSubstring,                const nsCStringComparator& aComparator )  {    nsACString::size_type src_len = aSource.Length(),                          sub_len = aSubstring.Length();    if (sub_len > src_len)      return PR_FALSE;    return Substring(aSource, src_len - sub_len, sub_len).Equals(aSubstring,                                                                 aComparator);  }