This test is intended to verify Break On Mutate support within the
HTML panel. This features allows to debug mutation events (DOMAttrModified,
DOMCharacterDataModified, DOMNodeInserted, DOMNodeRemoved)
Open Firebug and select the HTML panel.
Enable the Script panel and reload the page.
Click Break On Mutate button in the toolbar.
Click on one of the buttons below.
The debugger must stop JS execution and show the source code line that caused
the change in the DOM.