Shrink height of WINDOW if its buffer doesn't need so many lines.
More precisely, shrink WINDOW vertically to be as small as
possible, while still showing the full contents of its buffer.
WINDOW must be a live window and defaults to the selected one.
Do not shrink WINDOW to less than `window-min-height' lines. Do
nothing if the buffer contains more lines than the present window
height, or if some of the window's contents are scrolled out of
view, or if shrinking this window would also shrink another
window, or if the window is the only window of its frame.
Return non-nil if the window was shrunk, nil otherwise.