CopyUTF16toUTF8( const PRUnichar* aSource, nsACString& aDest )
CopyUTF16toUTF8( const nsAString& aSource, nsACString& aDest )
CopyUTF16toUTF8( const PRUnichar* aSource, nsACString& aDest )  {    aDest.Truncate();    AppendUTF16toUTF8(aSource, aDest);  }