resolve and reject returned from .defer() are not bound to promise

[rauno56]

1. What version of bluebird is the issue happening on? v3.7.2

2. What platform and version? All

3. Did this issue happen with earlier version of bluebird? Not sure.

Using (deprecated) defer API and passing resolve anywhere without having a promise with it results in an error:

     Uncaught TypeError: Cannot read property 'promise' of undefined
      at deferResolve (node_modules/bluebird/js/release/promise.js:754:32)
      at Timeout._onTimeout (test/index.test.ts:108:7)
      at listOnTimeout (internal/timers.js:554:17)
      at processTimers (internal/timers.js:497:7)

That's where resolve and reject are defined:

function deferResolve(v) {this.promise._resolveCallback(v);}
function deferReject(v) {this.promise._rejectCallback(v, false);}

To reproduce

const bluebird = require('bluebird');
const {
  promise,
  resolve,
} = bluebird.defer();
resolve();
/*
Uncaught:
TypeError: Illegal invocation, resolver resolve/reject must be called within a resolver context. Consider using the promise constructor instead.

    See http://goo.gl/sdkXL9

    at PromiseResolver.resolve.PromiseResolver.fulfill (/home/rauno/projects/bluebird/node_modules/bluebird/js/main/promise_resolver.js:88:15)
*/

Running only this example actually surprisingly gives me a different error from what I previously saw in the wild.

Would you consider accepting a patch that binds the callbacks to the promise?