diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/baseline/bug857580.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/baseline/bug857580.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+gczeal(2,10);
+var g = newGlobal();
+var dbg = new Debugger(g);
+dbg.onNewScript = function(script) {
+    fscript = script.getChildScripts()[0];
+}
+g.eval("function f(x) { arguments[0] = 3; return x }");
+fscript.setBreakpoint(0, {hit:function(frame) {
+    assertEq(frame.eval('x').return, 1);
+    gc();
+    return {return:42};
+}});
+assertEq(g.f(1), 42);