Form.Item help text causing jumpy content height

[samit4me]

• I have searched the issues of this repository and believe that this is not a duplicate.

Reproduction link

Steps to reproduce

• Click "Open Form" button.
• Enter some text into "Username" field.

What is expected?

The help/error message to disappear.

What is actually happening?

The help/error message does disappear but due to the animation and class "ant-form-item-with-help" the page changes in height which is jumpy when inside modals.

Please note that normal error messages (e.g. not using help) appear to work as expected, see the "Password" field.

Environment	Info
antd	4.0.0-rc.3
React	16.12.0
System	Ubuntu 18.04.3 LTS
Browser	Chrome 79

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In v3 this seems to work as expected https://codesandbox.io/s/tender-kare-qznfs

In v4 this causes the jumpy content height https://codesandbox.io/s/long-star-td4ir

[zombieJ]

ref #20836

[lzqtxwd]

这个问题仍然存在，上图是antd官网的截图。

[zombieJ]

能开个新的 issue 不？

[olegmdev]

+1