Flat Tree will be:
DIV	 id=sandbox
	DIV	 id=top
		DIV	 id=host
			DIV	 id=div1
			DIV	 id=div2


  mouseout

  mouseover
     @div2 (target: div2) (related: div1)
     @shadow-root (target: div2) (related: div1)
PASS successfullyParsed is true

TEST COMPLETE