code: function injectSiteAsync(content) {
          function genSiteAsyncMap() {
              var asyncList = [];
              fis.util.map(ret.map.res, function (id) {
                  var res = ret.ids[id];
                  if (res.isJsLike) {
                      asyncList.push(ret.ids[id]);
                  }
              });
              var subpath = (settings.subpath || 'pkg/map.js').replace(/^\//, '');
              return genAsyncMap(asyncList, subpath, null, settings.codeGen);
          }
  
          if (!siteAsync)
              siteAsync = genSiteAsyncMap();
          return injectAsyncWithMap(content, siteAsync);
      }
docs: 注入异步资源，将会注入整站资源表，每个页面均使用相同的资源表
  @param content
  @returns {XML|string|void}