fix($httpBackend): fixup patch for #9979

Builds ontop of c480462 from #9979
@caitp I hear what you say but maybe let's focus on landing this PR open a separate issue / PR if care about reworking all `undefined` to `void 0`.

What do you think about my comment regarding tests? Do you want to land yours that is similar to the existing one or just change the counter to start from 0?