Can you shrink it further?

[Andrei Alexandrescu via Digitalmars-d]

Had a bit of a good time with popFront for UTF, got to this: 
https://github.com/dlang/phobos/pull/4848. I suspect there are cleverer 
things that can be done. Can anyone make it tighter? Take a look at the 
disassembly referred to in the pull request. Thanks! -- Andrei