anchor.diff:    @override
     void ngOnDestroy() {
       super.ngOnDestroy();
  +    _subscription?.cancel();
  +    _subscription = null;
       textareaEl = null;
       popupSourceEl = null;
     }
  
positive.code:       var height = (value.nativeElement as Element).clientHeight;
        if (height != 0) {
          _inputLineHeight = height;
          _changeDetector
            ..markForCheck()
            // TODO(google): remove after the bug is fixed.
            ..detectChanges();
        }
      });
    }
  
negative.code: 
    final ChangeDetectorRef _changeDetector;
    final DomService _domService;
  
    StreamSubscription _subscription;
  
    @ViewChild('textareaEl')
    ElementRef textareaEl;
  