--- a/layout/generic/nsFrameList.h
+++ b/layout/generic/nsFrameList.h
@@ -48,16 +48,19 @@ namespace layout {
       // A special alias for kPrincipalList that suppress the reflow request that
       // is normally done when manipulating child lists.
       kNoReflowPrincipalList        = 0x8000
   };
 
   // A helper class for nsIFrame::Destroy[From].  It's defined here because
   // nsFrameList needs it and we can't use nsIFrame here.
   struct PostFrameDestroyData {
+    PostFrameDestroyData(const PostFrameDestroyData&) = delete;
+    PostFrameDestroyData() = default;
+
     AutoTArray<RefPtr<nsIContent>, 50> mAnonymousContent;
     AutoTArray<RefPtr<nsIContent>, 50> mGeneratedContent;
     void AddAnonymousContent(already_AddRefed<nsIContent>&& aContent) {
       mAnonymousContent.AppendElement(aContent);
     }
     void AddGeneratedContent(already_AddRefed<nsIContent>&& aContent) {
       mGeneratedContent.AppendElement(aContent);
     }