code: function Attr(name, value) {
      util.extend(this, {
          name: name,
          localName: name,
          value: value,
          specified: true,
          namespaceURI: null,
          prefix: null
      });
  }
docs: class Attr
  参考 http://www.w3.org/TR/dom/#attr
  
  @constructor
  @param {string} name attribute name
  @param {*} value attribute value