bug#14032: 24.3.50; regression: `modify-frame-parameters' no longer works correctly

[Drew Adams]

> Thanks.  For the record, here's a much easier way of reproducing
> the bug:
>   emacs -Q
>   Resize the frame by dragging one of its edges with the mouse
>   M-: (modify-frame-parameters nil '((fullscreen))) RET
> 
> IOW, the problem was that when 'fullscreen' was present in the frame
> parameters with a nil value, the frame dimensions were reset to the
> "original" size, which was recorded only during startup, and thus
> disregarded later changes of the frame dimensions.
> 
> I think I fixed this in revision 112114 on the trunk.

Thanks very much for persisting on this, Eli, including finding the simple
recipe.