Tests that adding a new rule works after switching nodes.

After adding new rule (inspected):
[expanded] 
element.style { ()
    font-size: 12px;

[expanded] 
foo, [$div#inspected, $]bar { (inspector-stylesheet:1 -> inspector-stylesheet:1:26)
    color: maroon;

[expanded] 
[$div$] { (user agent stylesheet)
    display: block;

After adding new rule (other):
[expanded] 
element.style { ()
    color: red;

[expanded] 
div#other { (inspector-stylesheet:5 -> inspector-stylesheet:5:12)

[expanded] 
div { (user agent stylesheet)
    display: block;

Revision added: inspector-stylesheet