* Extract for-of iterator handling to a helper
Dis greatly recudes the code size when for-of is used multiple times across the
codebase. Also, makes it easier to read what's happening in a compiled loop.
* Unify spec and loose code
* Legacy implementation fallback
* Update tmp var name
* Updates from review and after rebase
* for-of: IteratorClose spec compatibility.
See #3:
https://tc39.github.io/ecma262/#sec-iteratorclose
* Update spec fixtures for for-of.
* Fix IteratorClose case for remap-async-to-generator.
* Fix IteratorClose case for async-generator-function test output.
* Modify few tests according to iteratorClose fix.
* Fix iteratorClose for helpers.slicedToArray also.
* Update iteratorClose fixture for commonjs.
