Well it's not really the same. Firefox OS is literally the OS. Demanding that Chrome be allowed to run their C++ code would be like demanding that Google make

Well it's not really the same. Firefox OS is literally the OS. Demanding that Chrome be allowed to run their C++ code would be like demanding that Google makes it so that Firefox OS can be installed on Android phones, replacing the Android system. They don't do that, instead they offer up to developers the same facilities to write their apps that they reserve for their own apps. GMail for Android is written using the same language and APIs that you can use for your own application. Firefox OS is providing the same thing. They don't allow you to just replace the OS, which in this case is the browser, but all applications, including their own are written with the same APIs available to you the developer. They aren't writing some of their own apps in C++ and then demanding everyone else write in Javascript. Apple is writing their own JIT and then demanding that everyone else interpret, which is not at all equivalent. The difference here is that the browser is the OS. So the OS is at a certain level which you cannot replace or step into willy nilly. Think of it like Windows enforcing Hardware access through its drivers, not allowing you to just send whatever you want to someone's disk drive and possibly do damage to the device. In the same way, they enforce a level of Memory protection through the runtime, and after that they are on the same footing as you. We accept these constraints when we run OSs all the time, and I don't see it as being much different here.