>>Jyaif+J4
Actually, 3rd party browsers are now allowed on the App Store, with a few restrictions. Previous, section 3.3.2 of the developer agreement prevented the downloading and running of any code, except for JavaScript running inside iOS's JavaScriptCore. But the June 5th agreement allows any language and interpreter.
There are two limitations. The system makes it impossible to run unsigned code, so JIT compilation is out. Also, an app can't establish its own app store, so Google would have to get special permission for the Chrome Web Store.