Why do this? compile to native code directly if anything. Would you transform it to C first so you could edit the C? Then what if you want to make a big update using the Closure source? it will overwrite your changes.

This approach is not practical, perhaps I am failing to understand any logic as to why you would go with this approach. Portability (between processor architectures) is all I can think of but you will never achieve high performance if this is the case.

C coders write their code differently against different processors because all machines have different capabilities and resources (strength and weaknesses).