Javascript in this case has nothing to do with web browsers. It is simply a scripting language used to manipulate OSA (Apple's cross-application automation API in Mac OS X). Since OSA is not part of iOS, this likely won't affect iOS at all.
You actually can use Javascript to automate iOS apps running in Instruments (one of Apple's developer tools). This is used for automated UI testing in the iOS simulator or while your iOS device is tethered to a Mac. This has been around for a couple years and there's no indication that it will ever be permitted in released applications. There's actually no reason to enable it – it's only useful for snooping on apps (good for developers, bad for users).
You actually can use Javascript to automate iOS apps running in Instruments (one of Apple's developer tools). This is used for automated UI testing in the iOS simulator or while your iOS device is tethered to a Mac. This has been around for a couple years and there's no indication that it will ever be permitted in released applications. There's actually no reason to enable it – it's only useful for snooping on apps (good for developers, bad for users).