tell application "System Events"

  tell process "Safari"

    try

      set theGroup to 1st group of toolbar 1 of group 1 of window 1 whose class of text field 1 is text field

      set textValue to value of text field 1 of theGroup

    on error

      set theGroup to 1st group of toolbar 1 of window 1 whose class of text field 1 is text field

      set textValue to value of text field 1 of theGroup

    end try

  end tell

end tell