The directive controlled whether floating views should raise to the top
when the cursor is moved over it while using focus_follows_mouse. The
default was enabled, which is undesirable. For example, if you have two
floating views where one completely covers the other, the smaller one
would be inaccessible because moving the mouse over the bigger one would
raise it above the smaller one.
There is no known use case for having raise_floating enabled, so this
patch removes the directive and implements the raise_floating disabled
behaviour instead.
b9b1b0e566