script: use Element::create instead of DOM struct constructors (#39325)

Creating elements by directly calling their interface constructors leads
to some state not being intialized correctly (see #39285). It is also
not in line with the specifications as many of them refer to the
[`create an element`][1] algorithm when an element needs to be created,
which directly maps to `Element::create` in the script crate.

So, switch all such places where elements are created by script to use
`Element::create`.

[1]: https://dom.spec.whatwg.org/#concept-create-element

Testing: Existing WPT tests.

Fixes: #39285

Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>

components/script/dom/element.rs

@@ -2957,13 +2957,15 @@ impl Element {
             },
             // set context to the result of creating an element
             // given this's node document, "body", and the HTML namespace.
-            _ => DomRoot::upcast(HTMLBodyElement::new(
-                local_name!("body"),
+            _ => Element::create(
+                QualName::new(None, ns!(html), local_name!("body")),
                 None,
                 owner_doc,
+                ElementCreator::ScriptCreated,
+                CustomElementCreationMode::Asynchronous,
                 None,
                 can_gc,
-            )),
+            ),
         }
     }