The test verifies functionality of protocol method CSS.setStyleTexts and DOM.undo.
==== Initial style sheet text ====

#test { color: green; }

==== Style sheet text ====

#test {color: blue;}

Dumping matched rules: 
*#test* {    regular
    color: blue;
}
Dumping inherited rules: 
==== Style sheet text after clearing the stylesheet and DOM.Undo ====
<empty>