Created by: threadhead
Fixes legend margin-bottom spacing bug in WebKit browsers, retains proper spacing for non-webkit browsers.
Tested FF on PC/MAC: no double margins.
Tested IE8 on PC: no double margins.
Tested Safari MAC: correct margins.
Tested Chrome MAC/PC: correct margins.
Credit to: http://stackoverflow.com/questions/6063071/getting-webkit-to-pay-attention-to-legend-margins