initial implementation of function rest parameter support

[rbri]

arrow functions are not supported as of now

[rbri]

no comments for 2 months - @p-bakker, @gbrail are you still around?

[gbrail]

I have been having a really hard time finding time to work on Rhino these days as it's completely not part of my work world any more. Thanks for taking up a lot of the duties!

This particular PR looks good to me -- I also tried it and I can see that it handles the basics as described in the spec.

My only particular very minor comment is about the error message -- if we don't have a French translation of a particular message, can't we leave it out of the "_fr" message catalog and have Java fall back to the generic message? I see that you copied the English into the French message catalog and I don't believe that has worked in the past.

Thanks -- I am happy to merge this if we change that one tiny thing.

[rbri]

@gbrail good point -done

[gbrail]

This looks good now -- thanks!

[p-bakker]

@rbri the description says arrow functions aren't supported, but it's that (still) correct?

If arrows are also supported, I assume this PR completely closes #652?