t/158-wm_take_focus.t: avoid shift on scalars
t/158-wm_take_focus.t: avoid shift on scalars

This feature is forbidden in Perl ≥ 5.24:

  Experimental shift on scalar is now forbidden at
  ./t/158-wm_take_focus.t line 94, near ");"

i3/i3,avrelaun/i3,cornerman/i3,cornerman/i3,shdown/i3,shdown/i3,acrisci/i3,stapelberg/i3,avrelaun/i3,avrelaun/i3,i3/i3,stapelberg/i3,acrisci/i3,i3/i3,shdown/i3,strake/i3,Airblader/i3-original,stapelberg/i3,Airblader/i3,stapelberg/i3,Airblader/i3,Airblader/i3-original,acrisci/i3,strake/i3,cornerman/i3,shdown/i3,i3/i3,cornerman/i3,Airblader/i3-original,acrisci/i3,avrelaun/i3,Airblader/i3,strake/i3,Airblader/i3,acrisci/i3,Airblader/i3-original,strake/i3,Airblader/i3-original,strake/i3