Block new line inside list item no longer breaks list structure

[jacekbogdanski]

What is the purpose of this pull request?

Bug fix

Does your PR contain necessary tests?

All patches which change the editor code must include tests. You can always read more
on PR testing,
how to set the testing environment and
how to create tests
in the official CKEditor documentation.

This PR contains

• Unit tests
• Manual tests

What changes did you make?

The fix could be as easy as skipping whole list moving inside enterkey plugin when block item is a placeholder (new line added for block elements, without it you cannot create new list item by an enter key). Although, it causes an issue where block tag style is copied into following list items, which is unwanted behavior in this special use case.

Be aware that this fix doesn't creating break empty lines inside list item. They still can be added using shift+enter keystroke which creates br tags in the same node and in the result are not touched by the fix.

Closes #2205

[Comandeer]

Rebased onto latest master.

[Comandeer]

There is one hypothetical situation, in which this fix won't work. Imagine editor with CKEDITOR.ENTER_P enter mode, but with added div plugin. Content is copied from some trashy source (be it even Word!) and something like that is pasted into the editor:

<ul>
	<li>
		foo
		<div><br></div>
	</li>
</ul>

In such case pressing Enter inside div will delete the whole list item instead of adding new list item.

[Comandeer]

Please update version tag.

[jacekbogdanski]

If I'm right the issue can be easily resolved by dropping block element type.

[Comandeer]

LGTM! I've added changelog entry as it was missing.