diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/baseline/bug840984.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/baseline/bug840984.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,17 @@
+function foo() {
+    x = null;
+}
+function f() {
+    for (var i=0; i<99; i++) {
+	x = null;
+	if (i >= 97) {
+	    gc();
+	    gc();
+	    foo();
+	}
+	x = {};
+	if (i >= 97)
+	    foo();
+    }
+}
+f();