--- a/layout/style/CounterStyleManager.cpp
+++ b/layout/style/CounterStyleManager.cpp
@@ -2019,17 +2019,17 @@ CounterStyleManager::Disconnect()
   mStyles.Clear();
   mPresContext = nullptr;
 }
 
 CounterStyle*
 CounterStyleManager::BuildCounterStyle(nsIAtom* aName)
 {
   MOZ_ASSERT(NS_IsMainThread());
-  CounterStyle* data = mStyles.Get(aName);
+  CounterStyle* data = GetCounterStyle(aName);
   if (data) {
     return data;
   }
 
   // It is intentional that the predefined names are case-insensitive
   // but the user-defined names case-sensitive.
   StyleSetHandle styleSet = mPresContext->StyleSet();
   nsCSSCounterStyleRule* rule = styleSet->CounterStyleRuleForName(aName);

--- a/layout/style/CounterStyleManager.h
+++ b/layout/style/CounterStyleManager.h
@@ -319,16 +319,23 @@ public:
   void Disconnect();
 
   bool IsInitial() const
   {
     // only 'none' and 'decimal'
     return mStyles.Count() == 2;
   }
 
+  // Returns the counter style object for the given name from the style
+  // table if it is already built, and nullptr otherwise.
+  CounterStyle* GetCounterStyle(nsIAtom* aName) const {
+    return mStyles.Get(aName);
+  }
+  // Same as GetCounterStyle but try to build the counter style object
+  // rather than returning nullptr if that hasn't been built.
   CounterStyle* BuildCounterStyle(nsIAtom* aName);
 
   static CounterStyle* GetBuiltinStyle(int32_t aStyle);
   static CounterStyle* GetNoneStyle()
   {
     return GetBuiltinStyle(NS_STYLE_LIST_STYLE_NONE);
   }
   static CounterStyle* GetDecimalStyle()

--- a/layout/style/ServoBindings.cpp
+++ b/layout/style/ServoBindings.cpp
@@ -1268,19 +1268,28 @@ Gecko_SetImageOrientationAsFromImage(nsS
 void
 Gecko_CopyImageOrientationFrom(nsStyleVisibility* aDst,
                                const nsStyleVisibility* aSrc)
 {
   aDst->mImageOrientation = aSrc->mImageOrientation;
 }
 
 void
-Gecko_SetCounterStyleToName(CounterStylePtr* aPtr, nsIAtom* aName)
+Gecko_SetCounterStyleToName(CounterStylePtr* aPtr, nsIAtom* aName,
+                            RawGeckoPresContextBorrowed aPresContext)
 {
-  *aPtr = already_AddRefed<nsIAtom>(aName);
+  // Try resolving the counter style if possible, and keep it unresolved
+  // otherwise.
+  CounterStyleManager* manager = aPresContext->CounterStyleManager();
+  nsCOMPtr<nsIAtom> name = already_AddRefed<nsIAtom>(aName);
+  if (CounterStyle* style = manager->GetCounterStyle(name)) {
+    *aPtr = style;
+  } else {
+    *aPtr = name.forget();
+  }
 }
 
 void
 Gecko_SetCounterStyleToSymbols(CounterStylePtr* aPtr, uint8_t aSymbolsType,
                                nsACString const* const* aSymbols,
                                uint32_t aSymbolsCount)
 {
   nsTArray<nsString> symbols(aSymbolsCount);

--- a/layout/style/ServoBindings.h
+++ b/layout/style/ServoBindings.h
@@ -284,17 +284,18 @@ void Gecko_SetImageOrientation(nsStyleVi
                                double aRadians,
                                bool aFlip);
 void Gecko_SetImageOrientationAsFromImage(nsStyleVisibility* aVisibility);
 void Gecko_CopyImageOrientationFrom(nsStyleVisibility* aDst,
                                     const nsStyleVisibility* aSrc);
 
 // Counter style.
 // This function takes an already addrefed nsIAtom
-void Gecko_SetCounterStyleToName(mozilla::CounterStylePtr* ptr, nsIAtom* name);
+void Gecko_SetCounterStyleToName(mozilla::CounterStylePtr* ptr, nsIAtom* name,
+                                 RawGeckoPresContextBorrowed pres_context);
 void Gecko_SetCounterStyleToSymbols(mozilla::CounterStylePtr* ptr,
                                     uint8_t symbols_type,
                                     nsACString const* const* symbols,
                                     uint32_t symbols_count);
 void Gecko_SetCounterStyleToString(mozilla::CounterStylePtr* ptr,
                                    const nsACString* symbol);
 void Gecko_CopyCounterStyle(mozilla::CounterStylePtr* dst,
                             const mozilla::CounterStylePtr* src);