Jetpack: Infinite Scroll: improve compatibility with Carousel and Tiled Galleries modules.

Much like VideoPress (r815060), Tiled Galleries and Carousel require additional scripts to work properly with Infinite Scroll. Now, whenever either module is active, their scripts are enqueued to ensure errors don't break Infinite Scroll, and thus the site.

As part of this change, Tiled Galleries's asset enqueueing function is made static, so it can be referenced outside of the class.


git-svn-id: https://plugins.svn.wordpress.org/jetpack/trunk@815118 b8457f37-d9ea-0310-8a92-e5e31aec5664