[BUG]Adding items to an existing list will cause MatSelect to scrollToTop = 0.

[jvinhit]

Describe the bug

When update dataSource ( push new item to list ) mat-select scrollTop = 0;
When debugger check problem in here:

 /**
   * Scrolls the currently active option into the view if it is not yet visible.
   */
private adjustScrollTopToFitActiveOptionIntoView(): void {
    if (this.matSelect.panel && this.matSelect.options.length > 0) {
      const matOptionHeight = this.getMatOptionHeight();
      const activeOptionIndex = this.matSelect._keyManager.activeItemIndex || 0;
      const labelCount = _countGroupLabelsBeforeOption(activeOptionIndex, this.matSelect.options, this.matSelect.optionGroups);
      // If the component is in a MatOption, the activeItemIndex will be offset by one.
      const indexOfOptionToFitIntoView = (this.matOption ? -1 : 0) + labelCount + activeOptionIndex;
      const currentScrollTop = this.matSelect.panel.nativeElement.scrollTop;

      const searchInputHeight = this.innerSelectSearch.nativeElement.offsetHeight
      const amountOfVisibleOptions = Math.floor((SELECT_PANEL_MAX_HEIGHT - searchInputHeight) / matOptionHeight);

      const indexOfFirstVisibleOption = Math.round((currentScrollTop + searchInputHeight) / matOptionHeight) - 1;

      if (indexOfFirstVisibleOption >= indexOfOptionToFitIntoView) { ==>> bug indexOfOptionToFitIntoView = 0
        this.matSelect.panel.nativeElement.scrollTop = indexOfOptionToFitIntoView * matOptionHeight;
      } else if (indexOfFirstVisibleOption + amountOfVisibleOptions <= indexOfOptionToFitIntoView) {
        this.matSelect.panel.nativeElement.scrollTop = (indexOfOptionToFitIntoView + 1) * matOptionHeight - (SELECT_PANEL_MAX_HEIGHT - searchInputHeight);
      }
    }
  }

issue in conditional : if (indexOfFirstVisibleOption >= indexOfOptionToFitIntoView)
To Reproduce

Important Please provide a reproduction example. You can use https://stackblitz.com/github/bithost-gmbh/ngx-mat-select-search-example as a starting point

Expected behavior

Screenshots

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Additional context
Add any other context about the problem here.

[macjohnny]

@jvinhit thanks for reporting this issue.
I think this is a duplicate of #200, so let's continue the discussion there and close this one.