Update charts with new waitForCSSLoaded implementation

app/assets/javascripts/pages/projects/graphs/charts/index.js

@@ -5,7 +5,8 @@ import { __ } from '~/locale';
 import CodeCoverage from '../components/code_coverage.vue';
 import SeriesDataMixin from './series_data_mixin';
 
-waitForCSSLoaded(() => {
+document.addEventListener('DOMContentLoaded', () => {
+  waitForCSSLoaded(() => {
     const languagesContainer = document.getElementById('js-languages-chart');
     const codeCoverageContainer = document.getElementById('js-code-coverage-chart');
     const monthContainer = document.getElementById('js-month-chart');
@@ -150,4 +151,5 @@ waitForCSSLoaded(() => {
         });
       },
     });
+  });
 });

spec/frontend/helpers/startup_css_helper_spec.js

-import {
-  waitForCSSLoaded,
-} from '../../../app/assets/javascripts/helpers/startup_css_helper';
+import { waitForCSSLoaded } from '../../../app/assets/javascripts/helpers/startup_css_helper';
 
 describe('waitForCSSLoaded', () => {
   let mockedCallback;