My browser isn't running my JavaScript, it's running yours. In fact, the capability to run my own code in my own browser is being slowly but systematically removed from the browser.
When I said "you" I meant "the developer" not "the user": the class of devices that run C and not JS is also a class of devices that generally don't run third party code. If you aren't a hardware manufacturer (or trying to sell middleware to one) the fact the embedded systems run binaries that were programmed in C isn't in any way relevant.
