RichText: Combine nested `strong` tags to one

[hanneslsm]

What problem does this address?

Sometimes my client edit text and make it bold.
However, they somehow manage to create nested strong tags (I honestly don't know how but from my understanding they should't be able to when only using the editor). Because of this the variable font is rendered incorrectly.

Example

• First row: nested strong tags
  • 
• Second: manually removed to show you how the font should be rendered in Chrome (note the font-weight)
  • 

Which is displayed like this:

See: https://www.bittner-krull.de/produkte/rollout-planungstool/

What is your proposed solution?

The code should be cleaner by stripping strong tags / combining them to one if they are nested. And when one directly followed by another without any other characters in between.

[t-hamano]

This is very strange. I have tried to reproduce the problem but cannot. At least with the core inline formatting, this kind of nesting should not occur, and tags should be merged properly.

[hanneslsm]

I'll try to get more info on how my client edit texts and what exactly they do, so that we can reproduce this.

[kishanjasani]

@hanneslsm @t-hamano I was also not able to replicate: https://prnt.sc/3EmJTxDfvoio

Tested on Twenty Twenty Five theme.

[ktmn]

I can reproduce, just make a paragraph bold in the editor, copy some other bold text from some website, paste (Ctrl+V not Ctrl+Shift+V) into the paragraph in the editor - nested <strong> tags.

[t-hamano]

Good job @ktmn!

It turns out that this problem is more widespread. For example, you can create nested anchors. Nested strong tags are fine according to the spec, but nested anchors are invalid HTML.

The video below shows how to create nested anchors:

7cc8e2224ceca89b1a66a22450a3ad9c.mp4

One solution might be to remove all tags from the pasted HTML if the target is already wrapped in any tags.

[hanneslsm]

Thanks @ktmn ! I only got so far the info from my client that they were using a Word document and pasted the text. I tried to replicate it but couldn't yet. What you describe must be the reason. Thanks for finding out!

[yashjawale]

Attached #70823 as a fix, initially targets just nested <a> tags since its invalid according to spec
I can expand the same approach to target other tags after I know that it is indeed the right one 😅

At first I tried updating raw-handling API but it wasn't having any effect, then I modified RichText's paste-handler event listener & that appeared to do the trick