dialog.js always aimed at using the HTML5 dialog spec. Chrome just added experimental support for dialogs in it's dev branch: http://demo.agektmr.com/dialog/
We should let chrome use native dialogs when needed, it actually solves a bunch of messy issues, two of which are:
Attached is the patched used to make the following work (minus the scrolling element, that's hardcoded CSS).
What needs to be done is making sure our API can handle native dialogs when available and that pretty much means we need to not use jQuery UI or in a very different way than today to avoid wildly different UX between native and polyfill.