diff --git a/dom/base/AnonymousContent.cpp b/dom/base/AnonymousContent.cpp
index 448ce0ad1afe..1df36b048367 100644
--- a/dom/base/AnonymousContent.cpp
+++ b/dom/base/AnonymousContent.cpp
@@ -7,7 +7,6 @@
 #include "AnonymousContent.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/AnonymousContentBinding.h"
-#include "nsComputedDOMStyle.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsIDocument.h"
 #include "nsIDOMHTMLCollection.h"
@@ -209,29 +208,5 @@ AnonymousContent::WrapObject(JSContext* aCx,
   return AnonymousContentBinding::Wrap(aCx, this, aGivenProto, aReflector);
 }
 
-void
-AnonymousContent::GetComputedStylePropertyValue(const nsAString& aElementId,
-                                                const nsAString& aPropertyName,
-                                                DOMString& aResult,
-                                                ErrorResult& aRv)
-{
-  Element* element = GetElementById(aElementId);
-  if (!element) {
-    aRv.Throw(NS_ERROR_NOT_AVAILABLE);
-    return;
-  }
-
-  nsIPresShell* shell = element->OwnerDoc()->GetShell();
-  if (!shell) {
-    aRv.Throw(NS_ERROR_NOT_AVAILABLE);
-    return;
-  }
-
-  RefPtr<nsComputedDOMStyle> cs =
-    new nsComputedDOMStyle(element, NS_LITERAL_STRING(""), shell,
-                           nsComputedDOMStyle::eAll);
-  aRv = cs->GetPropertyValue(aPropertyName, aResult);
-}
-
 } // namespace dom
 } // namespace mozilla
diff --git a/dom/base/AnonymousContent.h b/dom/base/AnonymousContent.h
index b56c145956f6..fd3b59c440be 100644
--- a/dom/base/AnonymousContent.h
+++ b/dom/base/AnonymousContent.h
@@ -68,11 +68,6 @@ public:
                                 const Sequence<OwningNonNull<DOMRect>>& aRects,
                                 ErrorResult& aError);
 
-  void GetComputedStylePropertyValue(const nsAString& aElementId,
-                                     const nsAString& aPropertyName,
-                                     DOMString& aResult,
-                                     ErrorResult& aRv);
-
 private:
   ~AnonymousContent();
   nsCOMPtr<Element> mContentNode;
diff --git a/dom/webidl/AnonymousContent.webidl b/dom/webidl/AnonymousContent.webidl
index 8be69cd26f8e..6755fe598a63 100644
--- a/dom/webidl/AnonymousContent.webidl
+++ b/dom/webidl/AnonymousContent.webidl
@@ -77,12 +77,4 @@ interface AnonymousContent {
   [Throws]
   void setCutoutRectsForElement(DOMString elementId,
                                 sequence<DOMRect> rects);
-
-  /**
-   * Get the computed value of a property on an element inside this custom
-   * anonymous content.
-   */
-  [Throws]
-  DOMString? getComputedStylePropertyValue(DOMString elementId,
-                                           DOMString propertyName);
 };