Detect SVG support and add HTML class. By Todd Motto.
!function(){
function supportsSVG() { return !! document.createElementNS && !! document.createElementNS('http://www.w3.org/2000/svg','svg').createSVGRect }
if (supportsSVG()) document.documentElement.className += ' svg'
else document.documentElement.className += ' no-svg'
}()