There really isn't one. Symbian might be the closest that's still out there. Android would be somewhat quirky at best, and Apple wants you to use their toolchain.

Having said that, take a look at Appcelerator's Titanium (appcelerator.com) or AppMakr (appmakr.com). They both provide tools that enable you to create HTML/CSS/Javascript screens and also intermingle with other scripting languages to produce a compiled app for desktop, Apple, Android, and others.