code: function () {
  
          var $ = this.$;
          var contents = [];
  
          $('style').each(function () {
              var $this = $(this);
              var content = $this.text();
              contents.push(content);
          });
  
          if (this.options.debug) {
              console.log('');
              console.log('[DEBUG]', 'HtmlParser#getCssContents', this.file);
              console.log(contents);
          }
  
          return contents;
      }
docs: /*
  获取 style 标签的内容列表
  @return  {Array}