diff --git a/dom/base/Element.cpp b/dom/base/Element.cpp
index 72085b0148fb..854844d92e22 100644
--- a/dom/base/Element.cpp
+++ b/dom/base/Element.cpp
@@ -3103,47 +3103,14 @@ nsresult Element::PostHandleEventForLinks(EventChainPostVisitor& aVisitor) {
 
 void Element::GetLinkTarget(nsAString& aTarget) { aTarget.Truncate(); }
 
-static void nsDOMTokenListPropertyDestructor(void* aObject, nsAtom* aProperty,
-                                             void* aPropertyValue,
-                                             void* aData) {
-  nsDOMTokenList* list = static_cast<nsDOMTokenList*>(aPropertyValue);
-  NS_RELEASE(list);
-}
-
 static nsStaticAtom* const sPropertiesToTraverseAndUnlink[] = {
-    nsGkAtoms::sandbox, nsGkAtoms::sizes, nsGkAtoms::dirAutoSetBy, nullptr};
+    nsGkAtoms::dirAutoSetBy, nullptr};
 
 // static
 nsStaticAtom* const* Element::HTMLSVGPropertiesToTraverseAndUnlink() {
   return sPropertiesToTraverseAndUnlink;
 }
 
-nsDOMTokenList* Element::GetTokenList(
-    nsAtom* aAtom, const DOMTokenListSupportedTokenArray aSupportedTokens) {
-#ifdef DEBUG
-  const nsStaticAtom* const* props = HTMLSVGPropertiesToTraverseAndUnlink();
-  bool found = false;
-  for (uint32_t i = 0; props[i]; ++i) {
-    if (props[i] == aAtom) {
-      found = true;
-      break;
-    }
-  }
-  MOZ_ASSERT(found, "Trying to use an unknown tokenlist!");
-#endif
-
-  nsDOMTokenList* list = nullptr;
-  if (HasProperties()) {
-    list = static_cast<nsDOMTokenList*>(GetProperty(aAtom));
-  }
-  if (!list) {
-    list = new nsDOMTokenList(this, aAtom, aSupportedTokens);
-    NS_ADDREF(list);
-    SetProperty(aAtom, list, nsDOMTokenListPropertyDestructor);
-  }
-  return list;
-}
-
 nsresult Element::CopyInnerTo(Element* aDst, ReparseAttributes aReparse) {
   nsresult rv = aDst->mAttrs.EnsureCapacityToClone(mAttrs);
   NS_ENSURE_SUCCESS(rv, rv);
diff --git a/dom/base/Element.h b/dom/base/Element.h
index b8bded46909e..58cc122edbc5 100644
--- a/dom/base/Element.h
+++ b/dom/base/Element.h
@@ -1908,10 +1908,6 @@ class Element : public FragmentOrElement {
    */
   virtual void GetLinkTarget(nsAString& aTarget);
 
-  nsDOMTokenList* GetTokenList(
-      nsAtom* aAtom,
-      const DOMTokenListSupportedTokenArray aSupportedTokens = nullptr);
-
   enum class ReparseAttributes { No, Yes };
   /**
    * Copy attributes and state to another element
diff --git a/dom/html/HTMLIFrameElement.cpp b/dom/html/HTMLIFrameElement.cpp
index b475e108ac49..72dc463a955c 100644
--- a/dom/html/HTMLIFrameElement.cpp
+++ b/dom/html/HTMLIFrameElement.cpp
@@ -28,11 +28,13 @@ NS_IMPL_CYCLE_COLLECTION_CLASS(HTMLIFrameElement)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(HTMLIFrameElement,
                                                   nsGenericHTMLFrameElement)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mFeaturePolicy)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSandbox)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(HTMLIFrameElement,
                                                 nsGenericHTMLFrameElement)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mFeaturePolicy)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mSandbox)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_ADDREF_INHERITED(HTMLIFrameElement, nsGenericHTMLFrameElement)
diff --git a/dom/html/HTMLIFrameElement.h b/dom/html/HTMLIFrameElement.h
index ff1d6b2b9b66..70e576e800b4 100644
--- a/dom/html/HTMLIFrameElement.h
+++ b/dom/html/HTMLIFrameElement.h
@@ -66,7 +66,11 @@ class HTMLIFrameElement final : public nsGenericHTMLFrameElement {
     SetHTMLAttr(nsGkAtoms::name, aName, aError);
   }
   nsDOMTokenList* Sandbox() {
-    return GetTokenList(nsGkAtoms::sandbox, sSupportedSandboxTokens);
+    if (!mSandbox) {
+      mSandbox =
+          new nsDOMTokenList(this, nsGkAtoms::sandbox, sSupportedSandboxTokens);
+    }
+    return mSandbox;
   }
   bool AllowFullscreen() const {
     return GetBoolAttr(nsGkAtoms::allowfullscreen);
@@ -196,7 +200,8 @@ class HTMLIFrameElement final : public nsGenericHTMLFrameElement {
    */
   void AfterMaybeChangeAttr(int32_t aNamespaceID, nsAtom* aName, bool aNotify);
 
-  RefPtr<mozilla::dom::FeaturePolicy> mFeaturePolicy;
+  RefPtr<dom::FeaturePolicy> mFeaturePolicy;
+  RefPtr<nsDOMTokenList> mSandbox;
 };
 
 }  // namespace dom
diff --git a/dom/html/HTMLLinkElement.cpp b/dom/html/HTMLLinkElement.cpp
index 8a6183599a19..e8f387d8c1f6 100644
--- a/dom/html/HTMLLinkElement.cpp
+++ b/dom/html/HTMLLinkElement.cpp
@@ -75,12 +75,14 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(HTMLLinkElement,
                                                   nsGenericHTMLElement)
   tmp->nsStyleLinkElement::Traverse(cb);
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mRelList)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSizes)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(HTMLLinkElement,
                                                 nsGenericHTMLElement)
   tmp->nsStyleLinkElement::Unlink();
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mRelList)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mSizes)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED(HTMLLinkElement,
diff --git a/dom/html/HTMLLinkElement.h b/dom/html/HTMLLinkElement.h
index a52c3eb83be1..3b312754ff39 100644
--- a/dom/html/HTMLLinkElement.h
+++ b/dom/html/HTMLLinkElement.h
@@ -11,6 +11,7 @@
 #include "mozilla/dom/Link.h"
 #include "nsGenericHTMLElement.h"
 #include "nsStyleLinkElement.h"
+#include "nsDOMTokenList.h"
 
 namespace mozilla {
 class EventChainPostVisitor;
@@ -124,7 +125,12 @@ class HTMLLinkElement final : public nsGenericHTMLElement,
   static void ParseAsValue(const nsAString& aValue, nsAttrValue& aResult);
   static nsContentPolicyType AsValueToContentPolicy(const nsAttrValue& aValue);
 
-  nsDOMTokenList* Sizes() { return GetTokenList(nsGkAtoms::sizes); }
+  nsDOMTokenList* Sizes() {
+    if (!mSizes) {
+      mSizes = new nsDOMTokenList(this, nsGkAtoms::sizes);
+    }
+    return mSizes;
+  }
   void GetType(DOMString& aValue) { GetHTMLAttr(nsGkAtoms::type, aValue); }
   void SetType(const nsAString& aType, ErrorResult& aRv) {
     SetHTMLAttr(nsGkAtoms::type, aType, aRv);
@@ -183,6 +189,7 @@ class HTMLLinkElement final : public nsGenericHTMLElement,
   Maybe<SheetInfo> GetStyleSheetInfo() final;
 
   RefPtr<nsDOMTokenList> mRelList;
+  RefPtr<nsDOMTokenList> mSizes;
 
   // The "explicitly enabled" flag. This flag is set whenever the `disabled`
   // attribute is explicitly unset, and makes alternate stylesheets not be