Fixed the FirefoxOS slider knob highlighting, and took into account the FirefoxOS Simulator which frustratingly does support :active:hover css selector

 Fixed the FirefoxOS slider knob highlighting, and took into account the FirefoxOS Simulator which frustratingly does support :active:hover css selector

Enyo-DCO-1.1-Signed-off-by: Jason Robitaille <jason@canuckcoding.ca>