Auto merge of #8060 - nox:deref-js, r=Ms2ger

Implement Deref<Target=T> for JS<T> where T: Reflectable

We can only borrow `JS<T>` from rooted things, so it's safe to deref it.
The only types that provide mutable `JS<T>` things are `MutHeap<JS<T>>` and
`MutNullableHeap<JS<T>>`, which don't actually expose that they contain
`JS<T>` values.

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1 files changed, 3 insertions, 6 deletions

diff --git a/components/script/dom/domstringmap.rs b/components/script/dom/domstringmap.rs
index cfa5a8e0a1c..95f727c93cb 100644
--- a/components/script/dom/domstringmap.rs
+++ b/components/script/dom/domstringmap.rs
@@ -37,20 +37,17 @@ impl DOMStringMap {
 impl DOMStringMapMethods for DOMStringMap {
     // https://html.spec.whatwg.org/multipage/#dom-domstringmap-removeitem
     fn NamedDeleter(&self, name: DOMString) {
-        let element = self.element.root();
-        element.r().delete_custom_attr(name)
+        self.element.delete_custom_attr(name)
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-domstringmap-setitem
     fn NamedSetter(&self, name: DOMString, value: DOMString) -> ErrorResult {
-        let element = self.element.root();
-        element.r().set_custom_attr(name, value)
+        self.element.set_custom_attr(name, value)
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-domstringmap-nameditem
     fn NamedGetter(&self, name: DOMString, found: &mut bool) -> DOMString {
-        let element = self.element.root();
-        match element.r().get_custom_attr(name) {
+        match self.element.get_custom_attr(name) {
             Some(value) => {
                 *found = true;
                 value.clone()