lib/helpers/polyfill.js
function (Class, tag) {
        tag = tag.toLowerCase();
        if (!(tag in register)) {
          register[Class] = (register[Class] || []).concat(tag);
          register[tag] = (register[tag.toUpperCase()] = Class);
        }
      }
function (Class, tag) {
        tag = tag.toLowerCase();
        if (!(tag in register)) {
          register[Class] = (register[Class] || []).concat(tag);
          register[tag] = (register[tag.toUpperCase()] = Class);
        }
      }
(C) Andrea Giammarchi - @WebReflection - MIT Style