Auto merge of #25446 - pshaughn:fixme11868, r=jdm

Make getOwnPropertyDescriptor hold the correct value for indexed/named properties

This is towards #25036 and #25415; it could have far-reaching implications so I want to test it in isolation and see the results on the full test suite.

A few lines of code had a FIXME(#11868) despite that issue being closed, and looking for the pattern that was marked that way, I found one other unmarked instance of it. It doesn't immediately crash, and maybe it will pass some tests or fail some tests in informative ways.

EDIT: After adding an overlooked extended attribute to HTMLFormElement, this works very well indeed and seems to be worth merging!

---
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- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #25036

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- [ ] These changes do not require tests because ___

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4 files changed, 6 insertions, 9 deletions

diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index e0a5df68882..d79bc073e76 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -5147,8 +5147,7 @@ class CGDOMJSProxyHandler_getOwnPropertyDescriptor(CGAbstractExternMethod):
             attrs = "JSPROP_ENUMERATE"
             if self.descriptor.operations['IndexedSetter'] is None:
                 attrs += " | JSPROP_READONLY"
-            # FIXME(#11868) Should assign to desc.value, desc.get() is a copy.
-            fillDescriptor = ("desc.get().value = result_root.get();\n"
+            fillDescriptor = ("desc.value = result_root.get();\n"
                               "fill_property_descriptor(MutableHandle::from_raw(desc), proxy.get(), (%s) as u32);\n"
                               "return true;" % attrs)
             templateValues = {
@@ -5173,8 +5172,7 @@ class CGDOMJSProxyHandler_getOwnPropertyDescriptor(CGAbstractExternMethod):
                 attrs = " | ".join(attrs)
             else:
                 attrs = "0"
-            # FIXME(#11868) Should assign to desc.value, desc.get() is a copy.
-            fillDescriptor = ("desc.get().value = result_root.get();\n"
+            fillDescriptor = ("desc.value = result_root.get();\n"
                               "fill_property_descriptor(MutableHandle::from_raw(desc), proxy.get(), (%s) as u32);\n"
                               "return true;" % attrs)
             templateValues = {
@@ -5221,7 +5219,7 @@ if !expando.is_null() {
     }
 }
 """ + namedGet + """\
-desc.get().obj = ptr::null_mut();
+desc.obj = ptr::null_mut();
 return true;"""
 
     def definition_body(self):
diff --git a/components/script/dom/webidls/HTMLFormElement.webidl b/components/script/dom/webidls/HTMLFormElement.webidl
index 13ffbf4dfe8..744f6d84ca9 100644
--- a/components/script/dom/webidls/HTMLFormElement.webidl
+++ b/components/script/dom/webidls/HTMLFormElement.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://html.spec.whatwg.org/multipage/#htmlformelement
-[Exposed=Window]
+[Exposed=Window, LegacyUnenumerableNamedProperties]
 interface HTMLFormElement : HTMLElement {
   [HTMLConstructor] constructor();
 
diff --git a/components/script/dom/webidls/Window.webidl b/components/script/dom/webidls/Window.webidl
index f2cdeeb18a5..afd5183de33 100644
--- a/components/script/dom/webidls/Window.webidl
+++ b/components/script/dom/webidls/Window.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://html.spec.whatwg.org/multipage/#window
-[Global=Window, Exposed=Window]
+[Global=Window, Exposed=Window /*, LegacyUnenumerableNamedProperties */]
 /*sealed*/ interface Window : GlobalScope {
   // the current browsing context
   [Unforgeable] readonly attribute WindowProxy window;
diff --git a/components/script/dom/windowproxy.rs b/components/script/dom/windowproxy.rs
index 7fea1728c12..6aa0b9244cf 100644
--- a/components/script/dom/windowproxy.rs
+++ b/components/script/dom/windowproxy.rs
@@ -822,8 +822,7 @@ unsafe extern "C" fn getOwnPropertyDescriptor(
 
     assert!(desc.obj.is_null() || desc.obj == target.get());
     if desc.obj == target.get() {
-        // FIXME(#11868) Should assign to desc.obj, desc.get() is a copy.
-        desc.get().obj = proxy.get();
+        desc.obj = proxy.get();
     }
 
     true