LibJS+LibWeb: Wrap raw JS::Cell*/& fields in GCPtr/NonnullGCPtr

Author: https://github.com/mattco98
Commit: 7c0c1c8f49
Pull-request: https://github.com/SerenityOS/serenity/pull/17743
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibJS/Runtime/RegExpStringIterator.h

@@ -33,7 +33,7 @@ private:
 
     virtual void visit_edges(Cell::Visitor&) override;
 
-    Object& m_regexp_object;
+    NonnullGCPtr<Object> m_regexp_object;
     Utf16String m_string;
     bool m_global { false };
     bool m_unicode { false };