diff --git a/dom/base/Document.cpp b/dom/base/Document.cpp
index 4e742fc11779..0ac8662ad90c 100644
--- a/dom/base/Document.cpp
+++ b/dom/base/Document.cpp
@@ -6580,21 +6580,6 @@ void Document::RemoveStyleSheetFromStyleSets(StyleSheet& aSheet) {
   }
 }
 
-void Document::RemoveStyleSheet(StyleSheet& aSheet) {
-  RefPtr<StyleSheet> sheet = DocumentOrShadowRoot::RemoveSheet(aSheet);
-
-  if (!sheet) {
-    NS_ASSERTION(mInUnlinkOrDeletion, "stylesheet not found");
-    return;
-  }
-
-  if (!mIsGoingAway && sheet->IsApplicable()) {
-    RemoveStyleSheetFromStyleSets(*sheet);
-  }
-
-  sheet->ClearAssociatedDocumentOrShadowRoot();
-}
-
 void Document::InsertSheetAt(size_t aIndex, StyleSheet& aSheet) {
   DocumentOrShadowRoot::InsertSheetAt(aIndex, aSheet);
 
diff --git a/dom/base/Document.h b/dom/base/Document.h
index 38c6b0c4cd5b..ad448d4658af 100644
--- a/dom/base/Document.h
+++ b/dom/base/Document.h
@@ -1715,11 +1715,6 @@ class Document : public nsINode,
     InsertSheetAt(SheetCount(), *aSheet);
   }
 
-  /**
-   * Remove a stylesheet from the document
-   */
-  void RemoveStyleSheet(StyleSheet&);
-
   /**
    * Notify the document that the applicable state of the sheet changed
    * and that observers should be notified and style sets updated
diff --git a/dom/base/DocumentOrShadowRoot.cpp b/dom/base/DocumentOrShadowRoot.cpp
index a283f43417b3..d22250d421d4 100644
--- a/dom/base/DocumentOrShadowRoot.cpp
+++ b/dom/base/DocumentOrShadowRoot.cpp
@@ -78,16 +78,20 @@ void DocumentOrShadowRoot::InsertSheetAt(size_t aIndex, StyleSheet& aSheet) {
   mStyleSheets.InsertElementAt(aIndex, &aSheet);
 }
 
-already_AddRefed<StyleSheet> DocumentOrShadowRoot::RemoveSheet(
-    StyleSheet& aSheet) {
+void DocumentOrShadowRoot::RemoveStyleSheet(StyleSheet& aSheet) {
   auto index = mStyleSheets.IndexOf(&aSheet);
   if (index == mStyleSheets.NoIndex) {
-    return nullptr;
+    // We should only hit this case if we are unlinking
+    // in which case mStyleSheets should be cleared.
+    MOZ_ASSERT(mKind != Kind::Document ||
+               AsNode().AsDocument()->InUnlinkOrDeletion());
+    MOZ_ASSERT(mStyleSheets.IsEmpty());
+    return;
   }
   RefPtr<StyleSheet> sheet = std::move(mStyleSheets[index]);
   mStyleSheets.RemoveElementAt(index);
+  RemoveSheetFromStylesIfApplicable(*sheet);
   sheet->ClearAssociatedDocumentOrShadowRoot();
-  return sheet.forget();
 }
 
 void DocumentOrShadowRoot::RemoveSheetFromStylesIfApplicable(
diff --git a/dom/base/DocumentOrShadowRoot.h b/dom/base/DocumentOrShadowRoot.h
index a730a608125e..1bfa3cac49d4 100644
--- a/dom/base/DocumentOrShadowRoot.h
+++ b/dom/base/DocumentOrShadowRoot.h
@@ -88,6 +88,8 @@ class DocumentOrShadowRoot {
 
   void GetAdoptedStyleSheets(nsTArray<RefPtr<StyleSheet>>&) const;
 
+  void RemoveStyleSheet(StyleSheet&);
+
   Element* GetElementById(const nsAString& aElementId);
 
   /**
@@ -251,8 +253,6 @@ class DocumentOrShadowRoot {
    */
   void CloneAdoptedSheetsFrom(const DocumentOrShadowRoot&);
 
-  // Returns the reference to the sheet, if found in mStyleSheets.
-  already_AddRefed<StyleSheet> RemoveSheet(StyleSheet& aSheet);
   void InsertSheetAt(size_t aIndex, StyleSheet& aSheet);
 
   void AddSizeOfExcludingThis(nsWindowSizes&) const;
diff --git a/dom/base/ShadowRoot.cpp b/dom/base/ShadowRoot.cpp
index cedca7e1b71c..7d7072f0a89f 100644
--- a/dom/base/ShadowRoot.cpp
+++ b/dom/base/ShadowRoot.cpp
@@ -477,16 +477,6 @@ void ShadowRoot::RemoveSheetFromStyles(StyleSheet& aSheet) {
   ApplicableRulesChanged();
 }
 
-void ShadowRoot::RemoveSheet(StyleSheet& aSheet) {
-  RefPtr<StyleSheet> sheet = DocumentOrShadowRoot::RemoveSheet(aSheet);
-  MOZ_ASSERT(sheet || mStyleSheets.IsEmpty(),
-             "sheet should always be found, except after unlink, where we "
-             "should've cleared all stylesheets");
-  if (sheet && sheet->IsApplicable()) {
-    RemoveSheetFromStyles(*sheet);
-  }
-}
-
 void ShadowRoot::AddToIdTable(Element* aElement, nsAtom* aId) {
   IdentifierMapEntry* entry = mIdentifierMap.PutEntry(aId);
   if (entry) {
diff --git a/dom/base/ShadowRoot.h b/dom/base/ShadowRoot.h
index 6e8a263fe4d1..945e5460fc7a 100644
--- a/dom/base/ShadowRoot.h
+++ b/dom/base/ShadowRoot.h
@@ -74,7 +74,6 @@ class ShadowRoot final : public DocumentFragment,
   ShadowRootMode Mode() const { return mMode; }
   bool IsClosed() const { return mMode == ShadowRootMode::Closed; }
 
-  void RemoveSheet(StyleSheet&);
   void RemoveSheetFromStyles(StyleSheet&);
   void RuleAdded(StyleSheet&, css::Rule&);
   void RuleRemoved(StyleSheet&, css::Rule&);
diff --git a/dom/base/nsStyleLinkElement.cpp b/dom/base/nsStyleLinkElement.cpp
index cea272e9a360..1b5062fa6cf3 100644
--- a/dom/base/nsStyleLinkElement.cpp
+++ b/dom/base/nsStyleLinkElement.cpp
@@ -260,7 +260,7 @@ nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
     // disabled, since otherwise a sheet with a stale linking element pointer
     // will be hanging around -- not good!
     if (aOldShadowRoot) {
-      aOldShadowRoot->RemoveSheet(*mStyleSheet);
+      aOldShadowRoot->RemoveStyleSheet(*mStyleSheet);
     } else {
       aOldDocument->RemoveStyleSheet(*mStyleSheet);
     }
@@ -297,7 +297,7 @@ nsStyleLinkElement::DoUpdateStyleSheet(Document* aOldDocument,
       ShadowRoot* containingShadow = thisContent->GetContainingShadow();
       // Could be null only during unlink.
       if (MOZ_LIKELY(containingShadow)) {
-        containingShadow->RemoveSheet(*mStyleSheet);
+        containingShadow->RemoveStyleSheet(*mStyleSheet);
       }
     } else {
       doc->RemoveStyleSheet(*mStyleSheet);