Tests that elements panel does not receive events upon changes to the undiscovered nodes.

Appended
DOMAgent event fired. Should only happen once for output node: DOMNodeInserted DIV#undefined
Removed
Attribute modified
========= Result DOMAgent tree ========
#document[1]
    HTML[2]
        HEAD[3]
        BODY[4]
            P[5]
                [6]
            DIV[7]
            DIV[8]