Support single-value <select> elements (#35684)

https://github.com/user-attachments/assets/9aba75ff-4190-4a85-89ed-d3f3aa53d3b0



Among other things this adds a new `EmbedderMsg::ShowSelectElementMenu`
to tell the embedder to display a select popup at the given location.

This is a draft because some small style adjustments need to be made:
* the select element should always have the width of the largest option
* the border should be part of the shadow tree

Apart from that, it's mostly ready for review.

<details><summary>HTML for demo video</summary>

```html
<html>

<body>
<select id="c" name="choice">
  <option value="first">First Value</option>
  <option value="second">Second Value</option>
  <option value="third">Third Value</option>
</select>
</body>
</html>
```
</details>

---

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---------

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>
This commit is contained in:
Simon Wülker 2025-04-03 14:11:55 +02:00 committed by GitHub
parent 6e9d01b908
commit 0e99539dab
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32 changed files with 633 additions and 151 deletions

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@ -5,15 +5,9 @@
[interactive content <input> as first child of <label>]
expected: FAIL
[interactive content <select></select> as second child under <label>]
expected: FAIL
[interactive content <iframe></iframe> as second child under <label>]
expected: FAIL
[interactive content <select></select> as first child of <label>]
expected: FAIL
[interactive content <video tabindex=""></video> as second child under <label>]
expected: FAIL
@ -32,9 +26,6 @@
[interactive content <object usemap=""></object> as second child under <label>]
expected: FAIL
[interactive content <select></select> deeply nested under <label>]
expected: FAIL
[interactive content <textarea></textarea> as first child of <label>]
expected: FAIL
@ -67,4 +58,3 @@
[interactive content <textarea></textarea> as second child under <label>]
expected: FAIL

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@ -1,2 +0,0 @@
[closed-listbox-rendering.tentative.html]
expected: FAIL

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@ -1,2 +0,0 @@
[select-marker-end-aligned.tentative.html]
expected: FAIL