Modify selected method.

Did you meant to say this? @rhysd 
```vim
function! s:get_selected_text()
  let save_z = getreg('"', 1)
  let save_z_type = getregtype('"')

  try
    silent normal! gvy
    return @"
  finally
    call setreg('"', save_z, save_z_type)
  endtry
```