ripples (mat-checkbox, mat-option, etc...) cause scrolling in dialog

#### Bug, feature request, or proposal:
If a mat-checkbox is the last element in a mat-dialog-content it will cause the dialog to to have a scrollbar, even if the content has not reached it's max height.

#### What is the expected behavior?

There should be no scrolling if the dialog has room to grow.

#### What is the current behavior?

The dialog scrolls when a mat-checkbox is present.

#### What are the steps to reproduce?
https://stackblitz.com/edit/angular-material2-issue-dhosn1

Click the button, notice the dialog.

#### What is the use-case or motivation for changing an existing behavior?

It looks bad.

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

Whatever is used by stackblitz

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

まず、リンク先の StackBlitz の例で問題を再現し、次に、チェックボックスが最後の要素である場合の mat-dialog-content と mat-checkbox の ripple の相互作用を調べます。mat-checkbox または同様の ripple 対応コンポーネントが存在しても、拡張できる余地のあるダイアログにスクロールバーが表示されなくなれば完了です。

索引モデルが issue の本文から書いたものです。