Fix updated skeleton-line selector

Introduced in
https://gitlab.com/gitlab-org/gitlab-ce/commit/e9f557054869772955f86de3ac8138c7fc020564

spec/javascripts/repo/components/repo_loading_file_spec.js

@@ -13,7 +13,7 @@ describe('RepoLoadingFile', () => {
   function assertLines(lines) {
     lines.forEach((line, n) => {
       const index = n + 1;
-      expect(line.classList.contains(`line-of-code-${index}`)).toBeTruthy();
+      expect(line.classList.contains(`skeleton-line-${index}`)).toBeTruthy();
     });
   }