--- a/dom/base/Element.cpp
+++ b/dom/base/Element.cpp
@@ -1995,31 +1995,29 @@ nsDOMCSSAttributeDeclaration* Element::S
 }
 
 DeclarationBlock* Element::GetSMILOverrideStyleDeclaration() {
   Element::nsExtendedDOMSlots* slots = GetExistingExtendedDOMSlots();
   return slots ? slots->mSMILOverrideStyleDeclaration.get() : nullptr;
 }
 
 nsresult Element::SetSMILOverrideStyleDeclaration(
-    DeclarationBlock* aDeclaration, bool aNotify) {
+    DeclarationBlock* aDeclaration) {
   Element::nsExtendedDOMSlots* slots = ExtendedDOMSlots();
 
   slots->mSMILOverrideStyleDeclaration = aDeclaration;
 
-  if (aNotify) {
-    Document* doc = GetComposedDoc();
-    // Only need to request a restyle if we're in a document.  (We might not
-    // be in a document, if we're clearing animation effects on a target node
-    // that's been detached since the previous animation sample.)
-    if (doc) {
-      nsCOMPtr<nsIPresShell> shell = doc->GetShell();
-      if (shell) {
-        shell->RestyleForAnimation(this, eRestyle_StyleAttribute_Animations);
-      }
+  Document* doc = GetComposedDoc();
+  // Only need to request a restyle if we're in a document.  (We might not
+  // be in a document, if we're clearing animation effects on a target node
+  // that's been detached since the previous animation sample.)
+  if (doc) {
+    nsCOMPtr<nsIPresShell> shell = doc->GetShell();
+    if (shell) {
+      shell->RestyleForAnimation(this, eRestyle_StyleAttribute_Animations);
     }
   }
 
   return NS_OK;
 }
 
 bool Element::IsLabelable() const { return false; }
 

--- a/dom/base/Element.h
+++ b/dom/base/Element.h
@@ -342,22 +342,21 @@ class Element : public FragmentOrElement
 
   /**
    * Get the SMIL override style declaration for this element. If the
    * rule hasn't been created, this method simply returns null.
    */
   DeclarationBlock* GetSMILOverrideStyleDeclaration();
 
   /**
-   * Set the SMIL override style declaration for this element. If
-   * aNotify is true, this method will notify the document's pres
-   * context, so that the style changes will be noticed.
+   * Set the SMIL override style declaration for this element. This method will
+   * notify the document's pres context, so that the style changes will be
+   * noticed.
    */
-  nsresult SetSMILOverrideStyleDeclaration(DeclarationBlock* aDeclaration,
-                                           bool aNotify);
+  nsresult SetSMILOverrideStyleDeclaration(DeclarationBlock* aDeclaration);
 
   /**
    * Returns a new SMILAttr that allows the caller to animate the given
    * attribute on this element.
    */
   virtual UniquePtr<SMILAttr> GetAnimatedAttr(int32_t aNamespaceID,
                                               nsAtom* aName) {
     return nullptr;

--- a/layout/style/nsDOMCSSAttrDeclaration.cpp
+++ b/layout/style/nsDOMCSSAttrDeclaration.cpp
@@ -73,17 +73,17 @@ nsresult nsDOMCSSAttributeDeclaration::S
   MOZ_ASSERT_IF(!mIsSMILOverride, aClosureData);
 
   // The closure needs to have been called by now, otherwise we shouldn't be
   // getting here when the attribute hasn't changed.
   MOZ_ASSERT_IF(aClosureData, !aClosureData->mClosure);
 
   aDecl->SetDirty();
   return mIsSMILOverride
-             ? mElement->SetSMILOverrideStyleDeclaration(aDecl, true)
+             ? mElement->SetSMILOverrideStyleDeclaration(aDecl)
              : mElement->SetInlineStyleDeclaration(*aDecl, *aClosureData);
 }
 
 Document* nsDOMCSSAttributeDeclaration::DocToUpdate() {
   // We need OwnerDoc() rather than GetUncomposedDoc() because it might
   // be the BeginUpdate call that inserts mElement into the document.
   return mElement->OwnerDoc();
 }