LibWeb: Amend DomParser to make it compatible with TrustedTypes

Author: https://github.com/tete17
Commit: c591f8c14f
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6057
Reviewed-by: https://github.com/AtkinsSJ
Reviewed-by: https://github.com/Lubrsi ✅

Libraries/LibWeb/HTML/DOMParser.h

@@ -24,7 +24,7 @@ public:
 
     virtual ~DOMParser() override;
 
-    GC::Ref<DOM::Document> parse_from_string(StringView, Bindings::DOMParserSupportedType type);
+    WebIDL::ExceptionOr<GC::Root<DOM::Document>> parse_from_string(Utf16String, Bindings::DOMParserSupportedType type);
 
 private:
     explicit DOMParser(JS::Realm&);