EMSCRIPTEN_FETCH_SYNCHRONOUS in the main thread

[aharondavid]

Calling to emscripten_fetch with EMSCRIPTEN_FETCH_SYNCHRONOUS in the main thread can't be done.
so,I get over on it by the following code (c++):

if (emscripten_is_main_browser_thread())
{
    int handle = my_emscripten_fetch_in_thread(URL);// calling, in thread, to emscripten_fetch with EMSCRIPTEN_FETCH_SYNCHRONOUS 
    wait_for_the_thread(handle); //wait for the above thread 		
}

I know all about the risks when we lock the main thread, but, the above sample extremely simplify porting our c++ code to emscripten.

In Chrome\Edge, the above code is works. this is due to, I guess, to the fact that XMLHttpRequest doesn't going through the main thread.
In others browsers like Firefox, Safari, etc. the above code is stuck because of a dead lock.

do you think, in this case, that it's a matter of time that others browser will behave like Chrome\Edge ?
do you think that I shouldn't rely on the current behave of Chrome\Edge ?