TinyMCE: better way to remove spaces from empty paragraphs

[azaozz]

Follow up from #35890 and #38294.

It seems better to remove the white space chars (and  ) in the DOM after the post content is loaded instead of searching through the HTML string with regex. It could be slower in some cases, but is a lot "cleaner".

[azaozz]

In 39437.patch: remove empty spaces from paragraphs in the DOM instead of searching through the source HTML with regex.

[iseulde]

Looks good to me. Just not sure why we check for the length to be 10, it seems kind of random. We shouldn't unnecessarily check long strings of course, but still. If we are only inserting  , maybe we should only check for that?

[azaozz]

We are looking primarily for   but in innerHTML sometimes there can be couple of white space chars around it (also depends on the browser) so 10 is a good compromise between length and functionality. We want innerHTML to avoid paragraphs with inline tags.

[iseulde]

Looks good then. :)

[azaozz]

In 39902:

TinyMCE: improve removal of spaces from empty paragraphs when loading HTML in the editor.

Fixes #39437.