Autogrow unexpectedly applies fixed width

[nag5000]

Type of report

Bug

Provide detailed reproduction steps (if any)

1. Go to https://ckeditor.com/docs/ckeditor4/latest/examples/autogrow.html (ckeditor v4.16.2 at the moment)
2. Check that ckeditor container element doesn't have style="width: ...":
   
3. Focus the editor and insert 3+ lines to trigger auto grow.
4. Check the width again.

Expected result

ckeditor container element doesn't have style="width: ...".

Actual result

Other details

• Browser: Chrome 93.0.4577.63
• OS: Linux
• CKEditor version: 4.16.2
• Installed CKEditor plugins: autogrow

Related issue: #4372

config.width = '100%' doesn't help.

[Comandeer]

I can confirm the issue. It's connected with how CKEDITOR.editor#resize() method works – it requires both width and height even if we want to change only one of the dimensions. Probably the easiest fix would be to change this method's behaviour and add ability to change only one dimension.

[grumd]

Issue is that autogrow should have used null instead of width here to not set fixed width.

Here's how resize plugin did it:

[CKEditorBot]

Closed in #4919