Adds @supports to TidyCSS. Fixes Automattic/Jetpack#225
Resolve cross-domain error causing infinite-scroll to fail on HTTPS

Safari on Desktop and iOS consider HTTPS to HTTP requests as cross-domain.
So, for example, if a site is accessed via HTTPS on iOS Safari, infinite scroll will fail.

This bug affects many more users on wordpress.com, where all logged-in users
are switched to HTTPS.

The issue is resolved by checking the current protocol in infinity.js,
then switching http:// out for https:// in ajaxurl if needed.

This method is preferred over changing ajaxurl on the PHP side, beceause
server-side caching may cause protocol detection to be unreliable.

Video of bug in action:

https://www.youtube.com/watch?v=253litAe1sg
Tiled Gallery: Pass Carousel URLs through Photon.

Use `wp_get_attachment_image_src` instead of `wp_get_attachment_url` for `data-orig-file` in Tiled Galleries to trigger `filter_image_downsize` in Photon. This way the full image link in Carousel will point to an image served by Photon.
Tiled Gallery: Row containers to all galleries.

Circle and square galleries also have rows now, so that we can handle overflow
 when resizing for some themes more gracefully when content width changes due
 to for example a side bar in the twenty-fourteen theme.
Tiled Gallery: Group containers to all galleries.

Also square and circle galleries have groups now, so that overflow is more
graceful when for example zooming out in your browser to say 90%.
Merge pull request #511 from pdclark/infinite-scroll-fix-cross-domain-error

Resolve cross-domain error causing infinite-scroll to fail on HTTPS
Merge pull request #523 from rase-/fix/carousel-full-image-link

Tiled Gallery: Pass Carousel URLs through Photon.
Merge pull request #557 from rase-/add/rows

Added row and group containers to square and circle Tiled Galleries
Merge pull request #227 from kraftbj/github-225-csstidy

Adds @supports to TidyCSS.