code: function getPropHandler(tagName, attrName) {
      if (svgTags[tagName]) {
          return svgPropHandler;
      }
  
      var tagPropHandlers = elementPropHandlers[tagName];
      if (!tagPropHandlers) {
          tagPropHandlers = elementPropHandlers[tagName] = {};
      }
  
      var propHandler = tagPropHandlers[attrName];
      if (!propHandler) {
          propHandler = defaultElementPropHandlers[attrName] || defaultElementPropHandler;
          tagPropHandlers[attrName] = propHandler;
      }
  
      return propHandler;
  }
docs: 获取属性处理对象
  
  @param {string} tagName 元素tag
  @param {string} attrName 属性名
  @return {Object}