Sorting a mat-table with expandable rows causes rows to not expand on first click

#### Bug, feature request, or proposal:

Bug

#### What is the expected behavior?

Sorting the mat-table should not affect the expansion of the rows. The behavior should act as in the example table:
https://stackblitz.com/angular/keapqmllkjp?file=app%2Ftable-expandable-rows-example.ts

#### What is the current behavior?

After clicking on a column with sort capabilities and sorting the table, the expandable rows do not open on first click. Clicking a second time will expand the row.

#### What are the steps to reproduce?

https://stackblitz.com/edit/angular-c8kwxe?file=app%2Ftable-expandable-rows-example.ts
1.) Click on a column-header to sort the table
2.) Click the rows to expand
3.) Once you've clicked on a row and it does not expand, clicking on it again will result in nothing. To get it to expand, you have to click another row and then re-click the row again.

#### Which versions of Angular, Material, OS, TypeScript, browsers are affected?

#### Is there anything else we should know?

Oddly, if you cycle through all of the sorted states and get the rows to expand through each state, the rows will then behave normally after doing another sort.

リンクされた StackBlitz の例を使用して問題を再現します。まず app/table-expandable-rows-example.ts と、mat-table のソートおよび展開可能な行のインタラクションを確認します。ソート前後の動作を比較します。完了条件は、想定される例と同様に、どのソート状態の後でも最初のクリックで行が展開されることです。

索引モデルが issue の本文から書いたものです。