We always use PreventDefault for <select> element, which is problematic if modal
dialog is on as it prevents cancelling the dialog. We fix it by not blocking the
default action if <select> is not shown.
See Bug 1649278
ScrollbarStyles contains values of overflow, (over)scroll-behavior, etc.
The only one which is marginally related to scroll _bars_ is overflow, which can
be used to hide scrollbar (by making an element not scrollable) or enforce the
scrollbar to display.
It makes more sense to be called ScrollStyles as it's mainly concerning behavior
of scrolling, not scrollbars. Also, with the addition of scrollbar width
properties, the current name can be confusing.