As of WordPress 3.9, WordPress generates HTML5 Galleries if HTML5 is supported in the theme:
add_theme_support( 'html5' );
Originally in my theme development I did not declare HTML5 support and I've already published a few galleries which are using the old
DL HTML. Now I have declared HTML5 theme support as shown above, but WordPress won't regenerate my gallery even after saving the page or publishing a new gallery.
How do I "trick" WordPress or have WordPress start generating HTML5 galleries after my theme has been activate / activated?