You can now run WebAssembly on Cloudflare Workers(blog.cloudflare.com)

  // Really trivial malloc() implementation. We just allocate bytes sequentially from the start of
  // the heap, and reset the whole heap to empty at the start of each request.
  extern byte __heap_base;   // Start of heap -- symbol provided by compiler.

  byte* heap = NULL;         // Current heap position.
  void* last_malloc = NULL;  // Last value returned by malloc(), for trivial optimizations.

  void* malloc(size_t n) {
    last_malloc = heap;
    heap += n;
    return last_malloc;
  }

  byte *heap = &__heap_base;