src/third_party/mozjs-45/js/src/jit-test/tests/collections/Map-constructor-generator-3.js

// The argument to Map may be a generator-iterator that produces no values.

var m = new Map(x for (x of []));
assertEq(m.size, 0);

function none() {
    if (0) yield 0;
}
m = new Map(none());
assertEq(m.size, 0);