LPS-41268 - IE9 Dockbar cannot be seen on mobile screen widths

https://issues.liferay.com/browse/LPS-41268

Hey Jon,

I fixed the dockbar being white on mobile screen widths in IE9. Nate also asked me to add background-color in places where background-image didn't have a fall back. In custom_common.css .nav-account-controls li ul li a:hover i {}, I didn't add a fallback because in the dockbar dropdowns it makes the circle around the caret disappear on hover.

Patrick