It’d be entirely possible to make a backend for the compiler (like HiPE is for example) that compiles to webassembly.
Do note, webassembly is NOT just for running in the browser, it is a standard that defines a base bytecode for sandboxed execution. There are webassembly runners in C, Java, even an FPGA washing machine (yes really), none of which have Javascript or any of Javascript’s calls or libraries. It is just another backend, like x86 or ARM.
