Implement 'labels' attribute on 'labelable elements'

[frewsxcv]

[jdm]

@nox could you review this?

[nox]

-S-awaiting-review +S-awaiting-answer +S-needs-code-changes

---

Reviewed 20 of 20 files at r1, 1 of 1 files at r2.
Review status: all files reviewed at latest revision, 3 unresolved discussions, all commit checks successful.

---

^{components/script/dom/element.rs, line 1862 [r1] (raw file):}
Elements' IDs are stored as AttrValue::Atom values, we could use it if we use an atom for the label attribute on HTMLLabelElement. Either do it in that PR or file a follow-up issue.

---

^{components/script/dom/element.rs, line 1875 [r1] (raw file):}
You didn't include that rule:

If the for attribute is not specified, but the label element has a labelable element descendant, then the first such descendant in tree order is the label element's labeled control.

---

^{components/script/dom/element.rs, line 1855 [r2] (raw file):}
I'm not convinced by the LabelableElement trait, wouldn't it be simpler to define labels() on Element like how ParentNode's methods are defined on Node as helpers and called from the actual interfaces that implement them through an upcast

If traits are the way to go, we should file a follow-up to rewrite ParentNode and friends as traits.

Cc. @jdm @Ms2ger

---

Comments from the review on Reviewable.io

[Ms2ger]

Review status: all files reviewed at latest revision, 3 unresolved discussions, all commit checks successful.

---

^{components/script/dom/element.rs, line 1855 [r2] (raw file):}
I don't see a need for the trait either.

---

Comments from the review on Reviewable.io

[bors-servo]

☔ The latest upstream changes (presumably #7984) made this pull request unmergeable. Please resolve the merge conflicts.

[frewsxcv]

^{components/script/dom/element.rs, line 1855 [r2] (raw file):}
Aww I thought I was being clever with it :P

I'll definitely change it, but is there any reason not to? Extra unnecessary complexity? Seems like an easy way to isolate methods to certain Element types

---

Comments from the review on Reviewable.io

[frewsxcv]

Addressed all the comments. Let me know how this looks.

[frewsxcv]

I just noticed that some of this code will overlap with a couple of the methods on <label> elements. I'll plan on implementing those after this merges and making sure it doesn't get repeated.

https://html.spec.whatwg.org/multipage/forms.html#htmllabelelement

[nox]

-S-awaiting-review +S-needs-code-changes +S-awaiting-answer

---

Reviewed 12 of 12 files at r3.
Review status: all files reviewed at latest revision, 5 unresolved discussions, all commit checks successful.

---

^{components/script/dom/htmlelement.rs, line 321 [r3] (raw file):}
Please match against the type ID as usual.

---

^{components/script/dom/htmlelement.rs, line 347 [r3] (raw file):}
Can you explain to me this part of the code like I am 5? I can't make sense out of it. :/

---

^{components/script/dom/htmlinputelement.rs, line 344 [r3] (raw file):}
There is no need to upcast when calling window_from_node.

---

Comments from the review on Reviewable.io

[frewsxcv]

^{components/script/dom/htmlelement.rs, line 347 [r3] (raw file):}
I'm going to pause on this PR briefly and implement <label> control attribute because it might clear this up

---

Comments from the review on Reviewable.io

[bors-servo]

☔ The latest upstream changes (presumably #8178) made this pull request unmergeable. Please resolve the merge conflicts.

[frewsxcv]

@bors-servo try

[bors-servo]

⌛ Trying commit 0e8fd65 with merge e59c184...

[bors-servo]

💔 Test failed - mac-rel-wpt

[bors-servo]

☔ The latest upstream changes (presumably #8162) made this pull request unmergeable. Please resolve the merge conflicts.

[frewsxcv]

Rebased

[nox]

Just one nit and we are done.

-S-awaiting-review +S-needs-code-changes

---

Reviewed 8 of 8 files at r4, 8 of 8 files at r5.
Review status: all files reviewed at latest revision, 2 unresolved discussions, some commit checks failed.

---

^{components/script/dom/htmlinputelement.rs, line 344 [r3] (raw file):}
Please change this.

---

Comments from the review on Reviewable.io

[frewsxcv]

Comment has been addressed

[nox]

@bors-servo r+

---

Reviewed 2 of 2 files at r6.
Review status: all files reviewed at latest revision, 1 unresolved discussion.

---

Comments from the review on Reviewable.io

[bors-servo]

📌 Commit 9df3751 has been approved by nox

[bors-servo]

⌛ Testing commit 9df3751 with merge 0e70a1f...

[bors-servo]

☀️ Test successful - android, gonk, linux-dev, linux-rel, mac-dev-ref-unit, mac-rel-css, mac-rel-wpt