Flat Tree will be:
DIV	 id=sandbox
	DIV	 id=top
		DIV	 id=host
			DIV	 id=div1


  mouseout

  mouseover
     @div1 (target: div1) (related: div1)
     @shadow-root (target: div1) (related: div1)
PASS successfullyParsed is true

TEST COMPLETE