--- a/layout/style/ServoBindingList.h
+++ b/layout/style/ServoBindingList.h
@@ -178,17 +178,17 @@ SERVO_BINDING_FUNC(Servo_DeclarationBloc
 
 // presentation attributes
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_PropertyIsSet, bool,
                    RawServoDeclarationBlockBorrowed declarations,
                    nsCSSPropertyID property)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetIdentStringValue, void,
                    RawServoDeclarationBlockBorrowed declarations,
                    nsCSSPropertyID property,
-                   const nsAString& value)
+                   nsIAtom* value)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetKeywordValue, void,
                    RawServoDeclarationBlockBorrowed declarations,
                    nsCSSPropertyID property,
                    int32_t value)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetIntValue, void,
                    RawServoDeclarationBlockBorrowed declarations,
                    nsCSSPropertyID property,
                    int32_t value)

--- a/layout/style/ServoBindings.cpp
+++ b/layout/style/ServoBindings.cpp
@@ -1260,16 +1260,30 @@ Gecko_PropertyId_IsPrefEnabled(nsCSSProp
 
 void
 Gecko_CSSValue_Drop(nsCSSValueBorrowedMut aCSSValue)
 {
   aCSSValue->~nsCSSValue();
 }
 
 void
+Gecko_nsStyleFont_SetLang(nsStyleFont* aFont, nsIAtom* aAtom)
+{
+  already_AddRefed<nsIAtom> atom = already_AddRefed<nsIAtom>(aAtom);
+  aFont->mLanguage = atom;
+  aFont->mExplicitLanguage = true;
+}
+
+void
+Gecko_nsStyleFont_CopyLangFrom(nsStyleFont* aFont, const nsStyleFont* aSource)
+{
+  aFont->mLanguage = aSource->mLanguage;
+}
+
+void
 Gecko_LoadStyleSheet(css::Loader* aLoader,
                      ServoStyleSheet* aParent,
                      RawServoImportRuleBorrowed aImportRule,
                      const uint8_t* aURLString,
                      uint32_t aURLStringLength,
                      const uint8_t* aMediaString,
                      uint32_t aMediaStringLength)
 {

--- a/layout/style/ServoBindings.h
+++ b/layout/style/ServoBindings.h
@@ -334,16 +334,19 @@ void Gecko_CSSValue_SetKeyword(nsCSSValu
 void Gecko_CSSValue_SetPercentage(nsCSSValueBorrowedMut css_value, float percent);
 void Gecko_CSSValue_SetAngle(nsCSSValueBorrowedMut css_value, float radians);
 void Gecko_CSSValue_SetCalc(nsCSSValueBorrowedMut css_value, nsStyleCoord::CalcValue calc);
 void Gecko_CSSValue_SetFunction(nsCSSValueBorrowedMut css_value, int32_t len);
 void Gecko_CSSValue_Drop(nsCSSValueBorrowedMut css_value);
 NS_DECL_THREADSAFE_FFI_REFCOUNTING(nsCSSValueSharedList, CSSValueSharedList);
 bool Gecko_PropertyId_IsPrefEnabled(nsCSSPropertyID id);
 
+void Gecko_nsStyleFont_SetLang(nsStyleFont* font, nsIAtom* atom);
+void Gecko_nsStyleFont_CopyLangFrom(nsStyleFont* aFont, const nsStyleFont* aSource);
+
 const nsMediaFeature* Gecko_GetMediaFeatures();
 
 // Style-struct management.
 #define STYLE_STRUCT(name, checkdata_cb)                                       \
   void Gecko_Construct_Default_nsStyle##name(                                  \
     nsStyle##name* ptr,                                                        \
     RawGeckoPresContextBorrowed pres_context);                                 \
   void Gecko_CopyConstruct_nsStyle##name(nsStyle##name* ptr,                   \

--- a/layout/style/ServoSpecifiedValues.cpp
+++ b/layout/style/ServoSpecifiedValues.cpp
@@ -41,17 +41,18 @@ ServoSpecifiedValues::PropertyIsSet(nsCS
              "Presentation attribute mappers should never attempt to set the same property twice");
   return false;
 }
 
 void
 ServoSpecifiedValues::SetIdentStringValue(nsCSSPropertyID aId,
                                           const nsString& aValue)
 {
-  Servo_DeclarationBlock_SetIdentStringValue(mDecl, aId, aValue);
+  nsCOMPtr<nsIAtom> atom = NS_Atomize(aValue);
+  Servo_DeclarationBlock_SetIdentStringValue(mDecl, aId, atom);
 }
 
 void
 ServoSpecifiedValues::SetKeywordValue(nsCSSPropertyID aId, int32_t aValue)
 {
   Servo_DeclarationBlock_SetKeywordValue(mDecl, aId, aValue);
 }