refactor: cleaner code

Author: ulivz

packages/@vuepress/core/lib/app/components/ContentLoading.vue

@@ -20,15 +20,7 @@
 import { ContentLoader } from 'vue-content-loader'
 
 export default {
-  components: {
-    ContentLoader
-  },
-
-  data () {
-    return {
-      containerStyle: {}
-    }
-  }
+  components: { ContentLoader }
 }
 </script>