for-of loops, IteratorClose and the rest of the iterations in the spec

[Brendan Eich]

You want aggressive common sub-expression elimination on the specs (all 
of them, as bz noted).

Is there a common helper spec-only method that can be used both inside 
ES6 and by other specs?

Allen Wirfs-Brock wrote:
> Yes, except that I don't think the "body" of those loops can actually abnormally exit (or in the case of processing parameter lists, the iterator is an internal list iterator that doesn't have a 'return').  But that code should be reviewed to make sure I don't miss something.