diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/bug984830.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/bug984830.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,15 @@
+function getTestCaseResult(expected, actual) {
+      if (actual != expected)
+              return Math.abs(actual - expected) <= 1E-10;
+}
+function InstanceOf(object, constructor) {
+      while ( object != null )
+              object = object.__proto__;
+}
+function WorkerBee () {}
+function Engineer () {}
+Engineer.prototype = new WorkerBee();
+var pat = new Engineer();
+getTestCaseResult(pat.__proto__.__proto__.__proto__.__proto__ == Object.prototype);
+getTestCaseResult(InstanceOf(pat, Engineer));
+evaluate("getTestCaseResult( Object.prototype.__proto__ );", { compileAndGo: true });