Yes. This text is hidden, but we force it over the whole page, so that those yellow lines in the scroll bar in Chrome showing the position of search results are more or less accurate. You can temporary change the style of this dummy text layer and you will see what happens. Or you will not see, because it happens on pages which are not rendered with real text layer. :-) Try disabling rendering of real text layer temporary. This might be a good exercise to understand the code. :-)