[perl #114968] Typed arrays do not check type during list assignement

[Christian Bartolomaeus via RT]

This dies now (probably for a while already). I added a test to 
S09-typed-arrays/arrays.t with the following commit: 
https://github.com/perl6/roast/commit/26af8f842f11d0fca1f0479c67c15b206d10fcd8