diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/Map-constructor-generator-1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/Map-constructor-generator-1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,19 @@
+// The argument to Map can be a generator.
+
+var done = false;
+function data(n) {
+    var s = '';
+    for (var i = 0; i < n; i++) {
+        yield [s, i];
+        s += '.';
+    }
+    done = true;
+}
+
+var m = Map(data(50));
+assertEq(done, true);  // the constructor consumes the argument
+assertEq(m.size, 50);
+assertEq(m.get(""), 0);
+assertEq(m.get("....."), 5);
+assertEq(m.get(Array(49+1).join(".")), 49);
+assertEq(m.has(undefined), false);