scroll bars disappear in Chrome

when I activate this plugin my scrollbars in chrome diappear.
I went into /plugins/ajaxy-search-form/themes/common.css

if I comment out:

::-webkit-scrollbar {
	height: 10px;
	overflow: visible;
	width: 13px;
}

the scrollbars reappear.

I also appears that all of the styles within that declaration must be removed or the scrollbars will disappear(turn black, but the scrollbar still functions).
Is this style declaration necessary?

https://www.ads-software.com/extend/plugins/ajaxy-search-form/