bug#16923: 24.3.50; reression: `set-frame-size' loses mode line

[Drew Adams]

>  > height header-line: 0  mode-line: 14  divider: 0
> 
> Is this in a frame without mode line?

This is the frame that I tested the mode-line disappearance for.
Isn't that what you had in mind?

The frame had a mode line.  I used M-: (fit-frame) twice, which
removed the mode line.  I used (window--dump-frame), then reported
the contents of buffer *window-frame-dump*.