matMenu broken when using yPosition and Ivy

[james-schwartzkopf]

Reproduction

https://github.com/james-schwartzkopf/ng8-issues/tree/mat-menu-yPosition

Steps to reproduce:

1. yarn
2. yarn run build

Expected Behavior

Should compile cleanly and matMenu should appear in expected position.

Actual Behavior

Error:

    ERROR in src/app/app.component.html(15,32): Property 'yPosition' does not exist on type 'HTMLElement'.

Environment

• Angular: 8.2.1
• CDK/Material: 8.1.2

[crisbeto]

I wasn't able to reproduce it against angular/angular with the following unit test:

it('should fail', () => {
  class MatMenuBase {
    @Input() yPosition !: string;
  }

  @Component({
    template: '<ng-content></ng-content>',
    selector: 'mat-menu',
    exportAs: 'matMenu',
  })
  class MatMenu extends MatMenuBase {
  }

  @Directive({selector: '[matMenuTriggerFor]'})
  class MenuTrigger {
    @Input('matMenuTriggerFor') menu !: MatMenu;
  }

  @Component({
    template: `
      <button [matMenuTriggerFor]="menu">Open</button>
      <mat-menu #menu="matMenu" [yPosition]="'above'"></mat-menu>
    `
  })
  class MyComponent {
    @ViewChild(MenuTrigger, {static: false}) menuTrigger !: MenuTrigger;
  }

  TestBed.configureTestingModule({declarations: [MyComponent, MenuTrigger, MatMenu]});
  const fixture = TestBed.createComponent(MyComponent);
  fixture.detectChanges();

  expect(fixture.componentInstance.menuTrigger.menu.yPosition).toBe('above');
});

I wonder whether this isn't an issue with packaging.