ES2015 Iterator protocol impl. not complete (at least in for-of loops)

[p-bakker]

The return method is not called when breaking out or throwing inside a for-of loop

Testcase for the return method (from Compat tables):

var closed = false;
var iter = __createIterableObject([1, 2, 3], {
  'return': function(){ closed = true; return {}; }
});
for (var it of iter) break; // or throw '';
return closed;

Or with this stand-alone code, with expected output: Return called

var values = [];
var myIterator = {
  next() {
    return values.length ? {value: values.pop()}: {done: true};
  },
 return(value) { console.log('Return called'); return {done: true, value}}
};
myIterator[Symbol.iterator] = function() {return this}


for (var y of myIterator) break // or throw 1