Don't apply style backgrounds on buttons inside .has-form elements on top-bar-section.

Applying '.has-form' class on the list item at '.top-bar-section' adds extra padding for buttons.
Because of that padding when user points a cursor on the item but outside of the button, the button's background will disappear. This fix adds extra condition to check if element doesn't have '.has-form' and its decadent is not '.button' before applying the background style.