--- a/dom/xbl/nsXBLPrototypeBinding.cpp
+++ b/dom/xbl/nsXBLPrototypeBinding.cpp
@@ -228,19 +228,17 @@ nsXBLPrototypeBinding::GetAllowScripts()
 {
   return mXBLDocInfoWeak->GetScriptAccess();
 }
 
 bool
 nsXBLPrototypeBinding::LoadResources()
 {
   if (mResources) {
-    bool result;
-    mResources->LoadResources(&result);
-    return result;
+    return mResources->LoadResources();
   }
 
   return true;
 }
 
 nsresult
 nsXBLPrototypeBinding::AddResource(nsIAtom* aResourceType, const nsAString& aSrc)
 {

--- a/dom/xbl/nsXBLPrototypeResources.cpp
+++ b/dom/xbl/nsXBLPrototypeResources.cpp
@@ -42,23 +42,24 @@ nsXBLPrototypeResources::~nsXBLPrototype
 
 void
 nsXBLPrototypeResources::AddResource(nsIAtom* aResourceType, const nsAString& aSrc)
 {
   if (mLoader)
     mLoader->AddResource(aResourceType, aSrc);
 }
 
-void
-nsXBLPrototypeResources::LoadResources(bool* aResult)
+bool
+nsXBLPrototypeResources::LoadResources()
 {
-  if (mLoader)
-    mLoader->LoadResources(aResult);
-  else
-    *aResult = true; // All resources loaded.
+  if (mLoader) {
+    return mLoader->LoadResources();
+  }
+
+  return true; // All resources loaded.
 }
 
 void
 nsXBLPrototypeResources::AddResourceListener(nsIContent* aBoundElement)
 {
   if (mLoader)
     mLoader->AddResourceListener(aBoundElement);
 }

--- a/dom/xbl/nsXBLPrototypeResources.h
+++ b/dom/xbl/nsXBLPrototypeResources.h
@@ -24,17 +24,17 @@ class CSSStyleSheet;
 // The XBLPrototypeResources class
 
 class nsXBLPrototypeResources
 {
 public:
   explicit nsXBLPrototypeResources(nsXBLPrototypeBinding* aBinding);
   ~nsXBLPrototypeResources();
 
-  void LoadResources(bool* aResult);
+  bool LoadResources();
   void AddResource(nsIAtom* aResourceType, const nsAString& aSrc);
   void AddResourceListener(nsIContent* aElement);
   nsresult FlushSkinSheets();
 
   nsresult Write(nsIObjectOutputStream* aStream);
 
   void Traverse(nsCycleCollectionTraversalCallback &cb);
   void Unlink();

--- a/dom/xbl/nsXBLResourceLoader.cpp
+++ b/dom/xbl/nsXBLResourceLoader.cpp
@@ -76,29 +76,27 @@ nsXBLResourceLoader::nsXBLResourceLoader
 {
 }
 
 nsXBLResourceLoader::~nsXBLResourceLoader()
 {
   delete mResourceList;
 }
 
-void
-nsXBLResourceLoader::LoadResources(bool* aResult)
+bool
+nsXBLResourceLoader::LoadResources()
 {
   mInLoadResourcesFunc = true;
 
   if (mLoadingResources) {
-    *aResult = (mPendingSheets == 0);
     mInLoadResourcesFunc = false;
-    return;
+    return mPendingSheets == 0;
   }
 
   mLoadingResources = true;
-  *aResult = true;
 
   // Declare our loaders.
   nsCOMPtr<nsIDocument> doc = mBinding->XBLDocumentInfo()->GetDocument();
 
   mozilla::css::Loader* cssLoader = doc->CSSLoader();
   nsIURI *docURL = doc->GetDocumentURI();
   nsIPrincipal* docPrincipal = doc->NodePrincipal();
 
@@ -149,22 +147,23 @@ nsXBLResourceLoader::LoadResources(bool*
       {
         rv = cssLoader->LoadSheet(url, false, docPrincipal, EmptyCString(), this);
         if (NS_SUCCEEDED(rv))
           ++mPendingSheets;
       }
     }
   }
 
-  *aResult = (mPendingSheets == 0);
   mInLoadResourcesFunc = false;
 
   // Destroy our resource list.
   delete mResourceList;
   mResourceList = nullptr;
+
+  return mPendingSheets == 0;
 }
 
 // nsICSSLoaderObserver
 NS_IMETHODIMP
 nsXBLResourceLoader::StyleSheetLoaded(StyleSheet* aSheet,
                                       bool aWasAlternate,
                                       nsresult aStatus)
 {

--- a/dom/xbl/nsXBLResourceLoader.h
+++ b/dom/xbl/nsXBLResourceLoader.h
@@ -29,17 +29,17 @@ public:
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_CLASS(nsXBLResourceLoader)
 
   // nsICSSLoaderObserver
   NS_IMETHOD StyleSheetLoaded(mozilla::StyleSheet* aSheet,
                               bool aWasAlternate,
                               nsresult aStatus) override;
 
-  void LoadResources(bool* aResult);
+  bool LoadResources();
   void AddResource(nsIAtom* aResourceType, const nsAString& aSrc);
   void AddResourceListener(nsIContent* aElement);
 
   nsXBLResourceLoader(nsXBLPrototypeBinding* aBinding,
                       nsXBLPrototypeResources* aResources);
 
   void NotifyBoundElements();