diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/Object-unwrap-02.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/Object-unwrap-02.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,23 @@
+// Debugger.Object.prototype.unwrap unwraps Debugger.Objects referring to
+// cross-compartment wrappers.
+
+var dbg = new Debugger();
+
+var g1 = newGlobal();
+var dg1 = dbg.addDebuggee(g1);
+assertEq(dg1.unwrap(), dg1);
+
+var g2 = newGlobal();
+var dg2 = dbg.addDebuggee(g2);
+
+var dg1g2 = dg1.makeDebuggeeValue(g2);
+assertEq(dg1g2.global, dg1);
+assertEq(dg1g2.unwrap(), dg2);
+
+// Try an ordinary object, not a global.
+var g2o = g2.Object();
+var dg2o = dg2.makeDebuggeeValue(g2o);
+var dg1g2o = dg1.makeDebuggeeValue(g2o);
+assertEq(dg1g2o.global, dg1);
+assertEq(dg1g2o.unwrap(), dg2o);
+assertEq(dg1g2o.unwrap().unwrap(), dg2o);