LibWeb: Make DOMStringMap GC-allocated

Author: https://github.com/awesomekling
Commit: ae11d70b0c
Pull-request: https://github.com/SerenityOS/serenity/pull/14816
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibWeb/HTML/HTMLElement.cpp

@@ -30,7 +30,7 @@ namespace Web::HTML {
 
 HTMLElement::HTMLElement(DOM::Document& document, DOM::QualifiedName qualified_name)
     : Element(document, move(qualified_name))
-    , m_dataset(DOMStringMap::create(*this))
+    , m_dataset(JS::make_handle(DOMStringMap::create(*this)))
 {
 }