wdr-ui-element polution

[kekema]

Steps to reproduce:

1. go to https://www.webdatarocks.com/demos/js/pivot-table-demo/
2. right-click on an element outside of the pivot table, for example the Angular image for the Angular page - and from the dropdown menu select 'inspect'
3. in my observation, the class 'wdr-ui-element' is getting added at this very moment, so in this case to the IMG element.

Initially, number of 'wdr-ui-element' elements on the page is 53; after the 'inspect', it has become 54:

I tested also with my browser (chrome) in Incognito mode.

Thanks for a great component,
Karel.