bug#15886: 24.3.50; Incorrect window-text-height with non-zero line-spacing

[Eli Zaretskii]

> From: Robert Dallas Gray <mail@robertdallasgray.com>
> Date: Wed, 13 Nov 2013 19:23:19 +0000
> 
> On a graphical display, when `line-spacing' is non-zero,
> `window-text-height' reports an incorrect number; equally,
> `set-window-text-height' can't be used properly. This impacts on
> libraries which use `set-window-text-height' e.g. to attempt to size a
> window accurately.

Those libraries should use 'window-screen-lines' instead.

I think 'window-text-height' should continue doing what it does, as
many packages, and Emacs itself, depend on its current behavior.