enable failHard grunt-html-validation option; fixes 11876
enable failHard grunt-html-validation option; fixes 11876

BS3 commits: dcfe710fa4813da95dcfecc50a0581427d4cb491

2947721120/googlebt4,todc/todc-bootstrap,todc/todc-bootstrap,mozillo/todc-bootstrap,aaroncnhk/todc-bootstrap,up2vs/todc-bootstrap,todc/todc-bootstrap,2947721120/todc-bootstrap,ztx1491/todc-bootstrap