Auto merge of #13126 - splav:HTMLOptionElement.form#13111, r=metajack

Html option element.form#13111

<!-- Please describe your changes on the following line: -->
Add HTMLOptionElement form attribute support

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #13111 (github issue number if applicable).

<!-- Either: -->
- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/script/dom/htmloptionelement.rs

@@ -6,6 +6,7 @@ use dom::attr::Attr;
 use dom::bindings::codegen::Bindings::CharacterDataBinding::CharacterDataMethods;
 use dom::bindings::codegen::Bindings::HTMLOptionElementBinding;
 use dom::bindings::codegen::Bindings::HTMLOptionElementBinding::HTMLOptionElementMethods;
+use dom::bindings::codegen::Bindings::HTMLSelectElementBinding::HTMLSelectElementBinding::HTMLSelectElementMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::Root;
@@ -14,6 +15,8 @@ use dom::characterdata::CharacterData;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element};
 use dom::htmlelement::HTMLElement;
+use dom::htmlformelement::HTMLFormElement;
+use dom::htmloptgroupelement::HTMLOptGroupElement;
 use dom::htmlscriptelement::HTMLScriptElement;
 use dom::htmlselectelement::HTMLSelectElement;
 use dom::node::{Node, UnbindContext};
@@ -110,6 +113,19 @@ impl HTMLOptionElementMethods for HTMLOptionElement {
         self.upcast::<Node>().SetTextContent(Some(value))
     }
 
+    // https://html.spec.whatwg.org/multipage/#dom-option-form
+    fn GetForm(&self) -> Option<Root<HTMLFormElement>> {
+        let parent = self.upcast::<Node>().GetParentNode().and_then(|p|
+            if p.is::<HTMLOptGroupElement>() {
+                p.upcast::<Node>().GetParentNode()
+            } else {
+                Some(p)
+            }
+        );
+
+        parent.and_then(|p| p.downcast::<HTMLSelectElement>().and_then(|s| s.GetForm()))
+    }
+
     // https://html.spec.whatwg.org/multipage/#attr-option-value
     fn Value(&self) -> DOMString {
         let element = self.upcast::<Element>();

components/script/dom/webidls/HTMLOptionElement.webidl

@@ -9,7 +9,7 @@
 [Exposed=(Window,Worker)]
 interface HTMLOptionElement : HTMLElement {
              attribute boolean disabled;
-  //readonly attribute HTMLFormElement? form;
+             readonly attribute HTMLFormElement? form;
              attribute DOMString label;
              attribute boolean defaultSelected;
              attribute boolean selected;

tests/wpt/metadata/MANIFEST.json

@@ -37215,6 +37215,12 @@
     "deleted_reftests": {},
     "items": {
       "testharness": {
+        "html/semantics/forms/the-option-element/option-form.html": [
+          {
+            "path": "html/semantics/forms/the-option-element/option-form.html",
+            "url": "/html/semantics/forms/the-option-element/option-form.html"
+          }
+        ],
         "html/semantics/interactive-elements/the-dialog-element/dialog-open.html": [
           {
             "path": "html/semantics/interactive-elements/the-dialog-element/dialog-open.html",

tests/wpt/metadata/html/dom/interfaces.html.ini

@@ -3855,15 +3855,9 @@
   [HTMLOptGroupElement interface: document.createElement("optgroup") must inherit property "label" with the proper type (1)]
     expected: FAIL
 
-  [HTMLOptionElement interface: attribute form]
-    expected: FAIL
-
   [HTMLOptionElement interface: attribute index]
     expected: FAIL
 
-  [HTMLOptionElement interface: document.createElement("option") must inherit property "form" with the proper type (1)]
-    expected: FAIL
-
   [HTMLOptionElement interface: document.createElement("option") must inherit property "index" with the proper type (7)]
     expected: FAIL
 

tests/wpt/web-platform-tests/html/semantics/forms/the-option-element/option-form.html

@@ -0,0 +1,32 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>HTMLOptionElement.form</title>
+<link rel=author title="Sergey Alexandrov" href="mailto:splavgm@gmail.com">
+<link rel=help href="https://html.spec.whatwg.org/multipage/#dom-option-form">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<form id="form">
+    <select id="select">
+        <optgroup id="optgroup"></optgroup>
+    </select>
+</form>
+<div id=log></div>
+
+<script>
+test(function () {
+  var form = document.getElementById("form");
+  var select = document.getElementById("select");
+  var optgroup = document.getElementById("optgroup");
+
+  var o1 = document.createElement("option");
+  assert_equals(o1.form, null);
+
+  select.appendChild(o1);
+  assert_equals(o1.form, select.form);
+
+  var o2 = document.createElement("option");
+  select.appendChild(o2);
+  assert_equals(o2.form, select.form);
+
+}, "form");
+</script>