Controller defined by "classic" style does not work

Expected Behavior

As written on the documentation, the “classic” style should define new chart.

Current Behavior

Using the classic style, reported into documentation, you got an error:

Code

function Custom() {
  Chart.controllers.line.call(this, arguments);
}

Custom.prototype.draw = function() {
	Chart.controllers.line.prototype.draw.call(this, arguments);
}

Custom.id = 'myline';
Custom.defaults = Chart.defaults.line;

Chart.registry.addControllers(Custom);

Error

Uncaught Error: "myline" is not a registered controller.
    _get https://www.chartjs.org/dist/master/chart.js:5651
    getController https://www.chartjs.org/dist/master/chart.js:5601
    buildOrUpdateControllers https://www.chartjs.org/dist/master/chart.js:6131
    update https://www.chartjs.org/dist/master/chart.js:6168
    Chart https://www.chartjs.org/dist/master/chart.js:5949
    <anonymous> pen.js:44

Steps to Reproduce

https://codepen.io/stockinail/pen/MWKBvRQ

See the browser console log.

Environment

• Chart.js version: dist/master
• Browser name and version: FF 78.0.2

[kurkle]

I did open a PR, but if you want to improve the documentation, you’re welcome!

[kurkle]

https://codepen.io/kurkle/pen/oNbMMyG