diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/Set-constructor-2.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/Set-constructor-2.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,18 @@
+// The Set constructor can take an argument that is an array.
+
+var s = Set([]);
+assertEq(s.size, 0);
+assertEq(s.has(undefined), false);
+
+s = Set(["one", "two", "three"]);
+assertEq(s.size, 3);
+assertEq(s.has("one"), true);
+assertEq(s.has("eleventeen"), false);
+
+var a = [{}, {}, {}];
+s = Set(a);
+assertEq(s.size, 3);
+for (let obj of a)
+    assertEq(s.has(obj), true);
+assertEq(s.has({}), false);
+assertEq(s.has("three"), false);