Prerender removes [contentId] and breaks ion-menu

[tricki]

Stencil version:

 @stencil/core@1.8.2

I'm submitting a:

[x] bug report
[ ] feature request
[ ] support request => Please do not submit support requests here, use one of these channels: https://stencil-worldwide.herokuapp.com/ or https://forum.ionicframework.com/

Current behavior:
Prerender removes the ion-menu[contentId] attribute and causes a console warning and an error:

WARN: [DEPRECATED][ion-menu] Using the [main] attribute is deprecated, please use the "contentId" property instead:
BEFORE:
  <ion-menu>...</ion-menu>
  <div main>...</div>

AFTER:
  <ion-menu contentId="my-content"></ion-menu>
  <div id="my-content">...</div>

ERROR: Menu: must have a "content" element to listen for drag events on.

Expected behavior:
No warnings / errors.

Steps to reproduce:

1. Create a new Stencil project with the ionic-pwa starter.
2. Add <ion-menu contentId="main-content">.
3. Add an <ion-content contentId="main-content">.
4. Run npm run build --prerender and launch in the browser.

Related code:

import { Component, h } from '@stencil/core';

@Component({
  tag: 'app-root',
})
export class AppRoot {

  render() {
    return (
      <ion-app>
        <ion-menu contentId="main-content">
          <ion-header>
            <ion-toolbar>
              <ion-title>Menu</ion-title>
            </ion-toolbar>
          </ion-header>
        </ion-menu>
        <ion-content id="main-content">
          <h1>Hello</h1>
        </ion-content>
        <ion-nav />
      </ion-app>
    );
  }
}

Other information:
The same problem exists with <ion-split-pane> (split pane does not have a specified main node).

Workaround:
Add an additional content-id attribute to <ion-menu> with the same value as contentId.

[adamdbradley]

We'll fix this in ionic by adding reflect to the props. But for now you can still set just the attribute content-id. Hope that helps, thanks