src/third_party/mozjs-45/js/src/jit-test/tests/baseline/bug857580.js

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);