Optimize the Array#unshift method.
Optimize the Array#unshift method.

Adapt the "unshiftAllGuillaume" function from
https://gist.github.com/Mogztter/1d0005cc40555ae79c9e5b0a295ba20a ,
also fast-track when `objects.length == 0`.

Co-authored-by: Guillaume Grossetie <b9c33d7efece03e0b3a6bb4d39473c83a05f7862@gmail.com>

opal/opal,Mogztter/opal,Mogztter/opal,opal/opal,opal/opal,Mogztter/opal,Mogztter/opal,opal/opal