Problem/Motivation
When editing the source in a CKE5 field, you are unable to scroll.
Steps to reproduce
Step 1. Create a long text, formatted field within an entity (mine are on nodes).
Step 2. Create a new entity and enter some text into the CKE input box.
Step 3. Click the 'Source' button and make sure there is enough text to overflow the viewport.
Step 4. Using your mousewheel while your are focused on the CKE element, scroll down and see that there are no scrollbars within the element and that the entire page scrolls.
Proposed resolution
It appears that removing the `overflow:hidden` on the `.ck-source-editing-area textarea` element and also removing `white-space: pre-wrap` on `.ck-source-editing-area textarea, .ck-source-editing-area::after` seems to fix the issue.
It does not appear that this is upstream, based on the cke demo site I'm unable to reproduce the issue there, but i have been able to reproduce this on both a fresh d10 install and a d9 site that was recently upgraded to d10.
Note: This ONLY affects source view, and NOT the normal content entry view.