Properly change the kind of the given attribute in SetAttributeNode

The given argument may have special meaning for the element to which we add it,
and thus may have a specific representation to which we should switch the
attribute current's value.

Fixes #18357.

1 files changed, 10 insertions, 5 deletions

diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 11df4f6bd42..6896d25b9e4 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -1649,10 +1649,6 @@ impl ElementMethods for Element {
 
     // https://dom.spec.whatwg.org/#dom-element-setattributenode
     fn SetAttributeNode(&self, attr: &Attr) -> Fallible<Option<Root<Attr>>> {
-        // Workaround for https://github.com/servo/servo/issues/17366
-        // This ensures that if this is an "id" attr, its value is an Atom
-        attr.swap_value(&mut self.parse_plain_attribute(attr.local_name(), attr.Value()));
-
         // Step 1.
         if let Some(owner) = attr.GetOwnerElement() {
             if &*owner != self {
@@ -1660,6 +1656,15 @@ impl ElementMethods for Element {
             }
         }
 
+        let vtable = vtable_for(self.upcast());
+
+        // This ensures that the attribute is of the expected kind for this
+        // specific element. This is inefficient and should probably be done
+        // differently.
+        attr.swap_value(
+            &mut vtable.parse_plain_attribute(attr.local_name(), attr.Value()),
+        );
+
         // Step 2.
         let position = self.attrs.borrow().iter().position(|old_attr| {
             attr.namespace() == old_attr.namespace() && attr.local_name() == old_attr.local_name()
@@ -1688,7 +1693,7 @@ impl ElementMethods for Element {
             self.attrs.borrow_mut()[position] = JS::from_ref(attr);
             old_attr.set_owner(None);
             if attr.namespace() == &ns!() {
-                vtable_for(self.upcast()).attribute_mutated(
+                vtable.attribute_mutated(
                     &attr, AttributeMutation::Set(Some(&old_attr.value())));
             }