LibWeb: Add NamedNodeMap::getNamedItemNS()

This patch allows us to use method getNamedItemNS() of NamedNodeMap API.

Userland/Libraries/LibWeb/DOM/NamedNodeMap.cpp

@@ -80,6 +80,12 @@ Attr const* NamedNodeMap::get_named_item(StringView qualified_name) const
     return get_attribute(qualified_name);
 }
 
+// https://dom.spec.whatwg.org/#dom-namednodemap-getnameditemns
+Attr const* NamedNodeMap::get_named_item_ns(StringView namespace_, StringView local_name) const
+{
+    return get_attribute_ns(namespace_, local_name);
+}
+
 // https://dom.spec.whatwg.org/#dom-namednodemap-setnameditem
 WebIDL::ExceptionOr<Attr const*> NamedNodeMap::set_named_item(Attr& attribute)
 {

Userland/Libraries/LibWeb/DOM/NamedNodeMap.h

@@ -36,6 +36,7 @@ public:
     // Methods defined by the spec for JavaScript:
     Attr const* item(u32 index) const;
     Attr const* get_named_item(StringView qualified_name) const;
+    Attr const* get_named_item_ns(StringView namespace_, StringView local_name) const;
     WebIDL::ExceptionOr<Attr const*> set_named_item(Attr& attribute);
     WebIDL::ExceptionOr<Attr const*> remove_named_item(StringView qualified_name);
 

Userland/Libraries/LibWeb/DOM/NamedNodeMap.idl

@@ -6,7 +6,7 @@ interface NamedNodeMap {
 
     getter Attr? item(unsigned long index);
     getter Attr? getNamedItem(DOMString qualifiedName);
-    // Attr? getNamedItemNS(DOMString? namespace, DOMString localName);
+    Attr? getNamedItemNS(DOMString? namespace, DOMString localName);
 
     [CEReactions] Attr? setNamedItem(Attr attr);
     // [CEReactions] Attr? setNamedItemNS(Attr attr);