make tabIndex work (missing dcl/mini.js::mix change)

Requires dcl/mini.js::mix changed to add the catch block to work on IE or FF
mix = function(a, b){
       for(var n in b){
               try {
                       a[n] = b[n];
               } catch (e) {
                       Object.defineProperty(a, n, {
                               configurable: true,
                               writable: true,
                               enumerable: true,
                               value: b[n]
                       });
               }
       }