Tests that one session receives DOM notifications when the other modifies the DOM.

Modifying attribute value in 1
Attribute modified in 1: DIV[attr=newValue]
Attribute modified in 2: DIV[attr=newValue]

Removing attribute in 2
Attribute removed in 2: DIV[attr]
Attribute removed in 1: DIV[attr]

Removing node in 1
Node removed in 1: DIV
Node removed in 2: DIV

Undoing node removal in 1
Node inserted in 1: DIV
Node inserted in 2: DIV

Undoing attribute removal in 2
Attribute modified in 2: DIV[attr=newValue]
Attribute modified in 1: DIV[attr=newValue]