diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/Map-constructor-generator-3.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/Map-constructor-generator-3.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,8 @@
+// The argument to Map may be a generator-iterator that produces no values.
+
+assertEq(Map(x for (x of [])).size, 0);
+
+function none() {
+    if (0) yield 0;
+}
+assertEq(Map(none()).size, 0);