Binding a promise handler function to an object

I have some code like:

var bar = foo().then(function success(value) {
  // compute something from a value...
}, function failure(reason) {
  // handle an error...
});

How do I bind the failure function to the this object in the context of bar. I know I will have to use myFunc.bind(this) but what do I substitute in place of myFunc?