mat-form-field > textarea[matInput] shifts when resized to one row

#### Bug, feature request, or proposal:
When you resize a mat-form-field > textarea[matInput] down to one row, the contents of the textarea animate and shift downward, clipping.

#### What is the expected behavior?
There is no movement in the textarea or its content when it is resized.

#### What is the current behavior?
The content gets clipped.

#### What are the steps to reproduce?
https://stackblitz.com/edit/angular-material2-issue-bg2qqg?file=app/app.component.html

Shorten the textarea

Bug also present on https://material.angular.io/components/form-field/overview

#### What is the use-case or motivation for changing an existing behavior?
A user can easily shorten an expandable textarea and should not have the text shift and clip.

#### Which versions of Angular, Material, OS, TypeScript, browsers are affected?
Affects head Angular Material 2.

Linux Chrome, OS X Chrome.

But not present on Safari because textarea cannot resize smaller than it is on the demo page (locked at min 2 rows for me), unlike Chrome.

リンクされた StackBlitz の動作を、app/app.component.html から開始して再現し、Angular Material のフォームフィールド概要デモと比較してください。textarea[matInput] のサイズを 1 行に変更し、textarea の内容が移動したりクリップされたりしなくなったことを確認してください。

索引モデルが issue の本文から書いたものです。