N.B. this is a more actionable version of #2535 with repro links.

Environment

• Package version(s): 3.6.1
• Browser and OS versions: MacOS Chrome 68

Steps to reproduce

1. Use target: es6 in tsconfig.json.
2. Add a @HotkeysTarget and associated code as the docs describe.

Rationale

Per @giladgray

targeting es5 is a good practice for browser apps as es6+ is inconsistently supported.

In general, this makes sense to me. However, I would consider apps primarily intended for personal/internal use where modern browsers are implied as an exception (or Electron apps). Forwards compatibility also seems like a good way to 'future proof'.

Actual behavior

See https://codesandbox.io/s/7yp63vw621:

TypeError: Class constructor App cannot be invoked without 'new'
    at new HotkeysTargetClass (https://7yp63vw621.codesandbox.io/node_modules/@blueprintjs/core/lib/cjs/components/hotkeys/hotkeysTarget.js:20:50)
    at constructClassInstance (https://7yp63vw621.codesandbox.io/node_modules/react-dom/cjs/react-dom.development.js:6789:20)
    at updateClassComponent (https://7yp63vw621.codesandbox.io/node_modules/react-dom/cjs/react-dom.development.js:8324:9)
    at beginWork (https://7yp63vw621.codesandbox.io/node_modules/react-dom/cjs/react-dom.development.js:8966:16)
    <...snip...>

I think this breakage will also affect other decorators.

Expected behavior

Hotkeys work as expected.

See https://codesandbox.io/s/q3jk1n66mj.

Possible solution

I tried using the following to get around this but didn't have much luck:

function WrappedApp(props: IAppProps) {
  return new App(props);
}
WrappedApp.prototype = Object.create(App.prototype);

const AppWithHotkeys = HotkeysTarget(WrappedApp as any);
ReactDOM.render(<AppWithHotkeys {...(window as any).CONTEXT} />, document.getElementById('app'));

The render call from HotkeysTarget still never gets called.