bug#12253: Restore window start position

[martin rudalics]

> Usually Info widens the Info buffer, moves point using `goto-char' and
> finally narrows the buffer to the current node.  There is no way to use
> `set-window-point' in this workflow.  Other places (that move point
> after narrowing) could use the same function `goto-char' for consistency.

Conceptually, `goto-char' and `set-window-point' are idempotent with the
current buffer in the selected window.  Now *info* synchronizes
navigation in all windows showing *info*.  But if I split an *info*
window showing the (narrowed) beginning of *info* and do

(set-window-point (window-in-direction 'below) (point-max))

with the upper window selected, the lower window shows the (narrowed)
end of *info* and

(with-selected-window (window-in-direction 'below)
  (goto-char (point-max)))

does the same.  So I still miss you.

martin