On typing, existing content should be deleted with merge:true

[Reinmar]

The bug is described here: https://github.com/ckeditor/ckeditor5-engine/issues/670.

It's even better visible in http://localhost:8125/ckeditor5-presets/tests/manual/article.html where the content ends with a block quote. In this case, the block quote remains.

This happens because deleteContent() is called without merge: true:

https://github.com/ckeditor/ckeditor5-typing/blob/f26c3ba5a060e4644947b7f3a4097c0b3b06e0e2/src/input.js#L79

[Reinmar]

I can see that merge:true is passed in all cases but this... where it's a bug ;D

So, I'm going to change the merge option to doNotMerge so by default it will merge (https://github.com/ckeditor/ckeditor5-engine/issues/982).

[Reinmar]

All changes, including a test for this issue landed in ckeditor/ckeditor5-engine#983.