refactor(datepicker): adapt custom header demo for Ivy

Author: marclaval

src/dev-app/datepicker/datepicker-demo.ts

@@ -10,7 +10,6 @@ import {
   ChangeDetectionStrategy,
   ChangeDetectorRef,
   Component,
-  Host,
   Inject,
   ViewChild,
   Optional,
@@ -69,8 +68,7 @@ export class DatepickerDemo {
 export class CustomHeader<D> implements OnDestroy {
   private _destroyed = new Subject<void>();
 
-  constructor(@Host() private _calendar: MatCalendar<D>,
-              private _dateAdapter: DateAdapter<D>,
+  constructor(private _calendar: MatCalendar<D>, private _dateAdapter: DateAdapter<D>,
               @Inject(MAT_DATE_FORMATS) private _dateFormats: MatDateFormats,
               cdr: ChangeDetectorRef) {
     _calendar.stateChanges