Remove   from an empty paragraphs inside the visual editor

[iseulde]

An   is added to empty paragraphs to preserve them, but when inserting the content again in TinyMCE these spaces are not removed. So if I add an empty paragraph and come back later again to add something, a space is added before the cursor (And in most cases you don't even notice).

[iseulde]

The patch also fixes the case where two or more spaces are added and the paragraph is not kept.
That expressing also doesn't need capturing parentheses.

[iseulde]

#28341 was marked as a duplicate.

[azaozz]

In 28685:

TinyMCE: remove &nbsp from empty paragraphs inside the visual editor, props avryl, fixes #28282