--- a/dom/animation/KeyframeUtils.cpp
+++ b/dom/animation/KeyframeUtils.cpp
@@ -1015,26 +1015,24 @@ MakePropertyValuePair(nsCSSPropertyID aP
 
   result.mProperty = aProperty;
 
   if (aDocument->GetStyleBackendType() == StyleBackendType::Servo) {
     nsCString name = nsCSSProps::GetStringValue(aProperty);
 
     NS_ConvertUTF16toUTF8 value(aStringValue);
 
-    nsCString baseString;
     // FIXME this is using the wrong base uri (bug 1343919)
     RefPtr<css::URLExtraData> data =
       new css::URLExtraData(aDocument->GetDocumentURI(),
                             aDocument->GetDocumentURI(),
                             aDocument->NodePrincipal());
-    aDocument->GetDocumentURI()->GetSpec(baseString);
 
     RefPtr<RawServoDeclarationBlock> servoDeclarationBlock =
-      Servo_ParseProperty(&name, &value, &baseString, data).Consume();
+      Servo_ParseProperty(&name, &value, data).Consume();
 
     if (servoDeclarationBlock) {
       result.mServoDeclarationBlock = servoDeclarationBlock.forget();
     }
     return result;
   }
 
   nsCSSValue value;

--- a/dom/animation/TimingParams.cpp
+++ b/dom/animation/TimingParams.cpp
@@ -111,24 +111,22 @@ TimingParams::FromOptionsUnion(
 TimingParams::ParseEasing(const nsAString& aEasing,
                           nsIDocument* aDocument,
                           ErrorResult& aRv)
 {
   MOZ_ASSERT(aDocument);
 
   if (aDocument->IsStyledByServo()) {
     nsTimingFunction timingFunction;
-    nsCString baseString;
     // FIXME this is using the wrong base uri (bug 1343919)
     RefPtr<css::URLExtraData> data =
       new css::URLExtraData(aDocument->GetDocumentURI(),
                             aDocument->GetDocumentURI(),
                             aDocument->NodePrincipal());
-    aDocument->GetDocumentURI()->GetSpec(baseString);
-    if (!Servo_ParseEasing(&aEasing, &baseString, data, &timingFunction)) {
+    if (!Servo_ParseEasing(&aEasing, data, &timingFunction)) {
       aRv.ThrowTypeError<dom::MSG_INVALID_EASING_ERROR>(aEasing);
       return Nothing();
     }
 
     if (timingFunction.mType == nsTimingFunction::Type::Linear) {
       return Nothing();
     }
 

--- a/dom/svg/nsSVGElement.cpp
+++ b/dom/svg/nsSVGElement.cpp
@@ -1229,23 +1229,21 @@ MappedAttrParser::ParseMappedAttrValue(n
   if (propertyID != eCSSProperty_UNKNOWN) {
     bool changed = false; // outparam for ParseProperty.
     if (mBackend == StyleBackendType::Gecko) {
       mParser.ParseProperty(propertyID, aMappedAttrValue, mDocURI, mBaseURI,
                             mElement->NodePrincipal(), mDecl->AsGecko(), &changed, false, true);
     } else {
       NS_ConvertUTF16toUTF8 value(aMappedAttrValue);
       // FIXME (bug 1343964): Figure out a better solution for sending the base uri to servo
-      nsCString baseString;
       RefPtr<css::URLExtraData> data =
         new css::URLExtraData(mBaseURI, mDocURI, mElement->NodePrincipal());
-      mBaseURI->GetSpec(baseString);
       // FIXME (bug 1342559): Set SVG parsing mode for lengths
       changed = Servo_DeclarationBlock_SetPropertyById(mDecl->AsServo()->Raw(), propertyID,
-                                                       &value, false, &baseString, data);
+                                                       &value, false, data);
     }
 
     if (changed) {
       // The normal reporting of use counters by the nsCSSParser won't happen
       // since it doesn't have a sheet.
       if (nsCSSProps::IsShorthand(propertyID)) {
         CSSPROPS_FOR_SHORTHAND_SUBPROPERTIES(subprop, propertyID,
                                              CSSEnabledState::eForAllContent) {

--- a/layout/style/ServoBindingList.h
+++ b/layout/style/ServoBindingList.h
@@ -24,17 +24,16 @@ SERVO_BINDING_FUNC(Servo_Element_ClearDa
 // Styleset and Stylesheet management
 SERVO_BINDING_FUNC(Servo_StyleSheet_Empty, RawServoStyleSheetStrong,
                    mozilla::css::SheetParsingMode parsing_mode)
 SERVO_BINDING_FUNC(Servo_StyleSheet_FromUTF8Bytes, RawServoStyleSheetStrong,
                    mozilla::css::Loader* loader,
                    mozilla::ServoStyleSheet* gecko_stylesheet,
                    const nsACString* data,
                    mozilla::css::SheetParsingMode parsing_mode,
-                   const nsACString* base_url,
                    RawGeckoURLExtraData* extra_data)
 SERVO_BINDING_FUNC(Servo_ImportRule_GetSheet,
                    RawServoStyleSheetStrong,
                    const RawServoImportRuleBorrowed import_rule)
 SERVO_BINDING_FUNC(Servo_StyleSheet_ClearAndUpdate,
                    void,
                    RawServoStyleSheetBorrowed stylesheet,
                    mozilla::css::Loader* loader,
@@ -114,21 +113,19 @@ SERVO_BINDING_FUNC(Servo_NamespaceRule_G
                    RawServoNamespaceRuleBorrowed rule)
 SERVO_BINDING_FUNC(Servo_NamespaceRule_GetURI, nsIAtom*,
                    RawServoNamespaceRuleBorrowed rule)
 
 // Animations API
 SERVO_BINDING_FUNC(Servo_ParseProperty,
                    RawServoDeclarationBlockStrong,
                    const nsACString* property, const nsACString* value,
-                   const nsACString* base,
                    RawGeckoURLExtraData* data)
 SERVO_BINDING_FUNC(Servo_ParseEasing, bool,
                    const nsAString* easing,
-                   const nsACString* base,
                    RawGeckoURLExtraData* data,
                    nsTimingFunctionBorrowedMut output)
 SERVO_BINDING_FUNC(Servo_GetComputedKeyframeValues, void,
                    RawGeckoKeyframeListBorrowed keyframes,
                    ServoComputedValuesBorrowed style,
                    ServoComputedValuesBorrowedOrNull parent_style,
                    RawServoStyleSetBorrowed set,
                    RawGeckoComputedKeyframeValuesListBorrowedMut result)
@@ -154,17 +151,16 @@ SERVO_BINDING_FUNC(Servo_AnimationValue_
                    RefPtr<nsCSSValueSharedList>* list)
 SERVO_BINDING_FUNC(Servo_AnimationValue_DeepEqual, bool,
                    RawServoAnimationValueBorrowed,
                    RawServoAnimationValueBorrowed)
 
 // Style attribute
 SERVO_BINDING_FUNC(Servo_ParseStyleAttribute, RawServoDeclarationBlockStrong,
                    const nsACString* data,
-                   const nsACString* base,
                    RawGeckoURLExtraData* extra_data)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_CreateEmpty,
                    RawServoDeclarationBlockStrong)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_Clone, RawServoDeclarationBlockStrong,
                    RawServoDeclarationBlockBorrowed declarations)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_Equals, bool,
                    RawServoDeclarationBlockBorrowed a,
                    RawServoDeclarationBlockBorrowed b)
@@ -187,23 +183,21 @@ SERVO_BINDING_FUNC(Servo_DeclarationBloc
                    nsCSSPropertyID property, nsAString* value)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_GetPropertyIsImportant, bool,
                    RawServoDeclarationBlockBorrowed declarations,
                    const nsACString* property)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetProperty, bool,
                    RawServoDeclarationBlockBorrowed declarations,
                    const nsACString* property,
                    const nsACString* value, bool is_important,
-                   const nsACString* base,
                    RawGeckoURLExtraData* data)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_SetPropertyById, bool,
                    RawServoDeclarationBlockBorrowed declarations,
                    nsCSSPropertyID property,
                    const nsACString* value, bool is_important,
-                   const nsACString* base,
                    RawGeckoURLExtraData* data)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_RemoveProperty, void,
                    RawServoDeclarationBlockBorrowed declarations,
                    const nsACString* property)
 SERVO_BINDING_FUNC(Servo_DeclarationBlock_RemovePropertyById, void,
                    RawServoDeclarationBlockBorrowed declarations,
                    nsCSSPropertyID property)
 

--- a/layout/style/ServoDeclarationBlock.cpp
+++ b/layout/style/ServoDeclarationBlock.cpp
@@ -11,21 +11,19 @@
 
 namespace mozilla {
 
 /* static */ already_AddRefed<ServoDeclarationBlock>
 ServoDeclarationBlock::FromCssText(const nsAString& aCssText,
                                    css::URLExtraData* aExtraData)
 {
   NS_ConvertUTF16toUTF8 value(aCssText);
-  nsCString baseString;
   // FIXME (bug 1343964): Figure out a better solution for sending the base uri to servo
-  aExtraData->BaseURI()->GetSpec(baseString);
   RefPtr<RawServoDeclarationBlock>
-    raw = Servo_ParseStyleAttribute(&value, &baseString, aExtraData).Consume();
+    raw = Servo_ParseStyleAttribute(&value, aExtraData).Consume();
   RefPtr<ServoDeclarationBlock> decl = new ServoDeclarationBlock(raw.forget());
   return decl.forget();
 }
 
 void
 ServoDeclarationBlock::GetPropertyValue(const nsAString& aProperty,
                                         nsAString& aValue) const
 {

--- a/layout/style/ServoStyleSheet.cpp
+++ b/layout/style/ServoStyleSheet.cpp
@@ -85,25 +85,21 @@ ServoStyleSheet::ParseSheet(css::Loader*
                             nsIURI* aSheetURI,
                             nsIURI* aBaseURI,
                             nsIPrincipal* aSheetPrincipal,
                             uint32_t aLineNumber)
 {
   RefPtr<css::URLExtraData> extraData =
     new css::URLExtraData(aBaseURI, aSheetURI, aSheetPrincipal);
 
-  nsCString baseString;
-  nsresult rv = aBaseURI->GetSpec(baseString);
-  NS_ENSURE_SUCCESS(rv, rv);
-
   NS_ConvertUTF16toUTF8 input(aInput);
   if (!Inner()->mSheet) {
     Inner()->mSheet =
-      Servo_StyleSheet_FromUTF8Bytes(aLoader, this, &input, mParsingMode,
-                                     &baseString, extraData).Consume();
+      Servo_StyleSheet_FromUTF8Bytes(aLoader, this, &input,
+                                     mParsingMode, extraData).Consume();
   } else {
     Servo_StyleSheet_ClearAndUpdate(Inner()->mSheet, aLoader,
                                     this, &input, extraData);
   }
 
   return NS_OK;
 }
 

--- a/layout/style/nsDOMCSSDeclaration.cpp
+++ b/layout/style/nsDOMCSSDeclaration.cpp
@@ -303,23 +303,21 @@ nsDOMCSSDeclaration::ParsePropertyValue(
   bool changed;
   if (decl->IsGecko()) {
     nsCSSParser cssParser(env.mCSSLoader);
     cssParser.ParseProperty(aPropID, aPropValue,
                             env.mSheetURI, env.mBaseURI, env.mPrincipal,
                             decl->AsGecko(), &changed, aIsImportant);
   } else {
     NS_ConvertUTF16toUTF8 value(aPropValue);
+    // FIXME (bug 1343964): Figure out a better solution for sending the base uri to servo
     RefPtr<css::URLExtraData> data =
       new css::URLExtraData(env.mBaseURI, env.mSheetURI, env.mPrincipal);
-    nsCString baseString;
-    // FIXME (bug 1343964): Figure out a better solution for sending the base uri to servo
-    env.mBaseURI->GetSpec(baseString);
     changed = Servo_DeclarationBlock_SetPropertyById(
-      decl->AsServo()->Raw(), aPropID, &value, aIsImportant, &baseString, data);
+      decl->AsServo()->Raw(), aPropID, &value, aIsImportant, data);
   }
   if (!changed) {
     // Parsing failed -- but we don't throw an exception for that.
     return NS_OK;
   }
 
   return SetCSSDeclaration(decl);
 }
@@ -357,20 +355,18 @@ nsDOMCSSDeclaration::ParseCustomProperty
     cssParser.ParseVariable(propName, aPropValue, env.mSheetURI,
                             env.mBaseURI, env.mPrincipal, decl->AsGecko(),
                             &changed, aIsImportant);
   } else {
     NS_ConvertUTF16toUTF8 property(aPropertyName);
     NS_ConvertUTF16toUTF8 value(aPropValue);
     RefPtr<css::URLExtraData> data =
       new css::URLExtraData(env.mBaseURI, env.mSheetURI, env.mPrincipal);
-    nsCString baseString;
-    env.mBaseURI->GetSpec(baseString);
     changed = Servo_DeclarationBlock_SetProperty(
-      decl->AsServo()->Raw(), &property, &value, aIsImportant, &baseString, data);
+      decl->AsServo()->Raw(), &property, &value, aIsImportant, data);
   }
   if (!changed) {
     // Parsing failed -- but we don't throw an exception for that.
     return NS_OK;
   }
 
   return SetCSSDeclaration(decl);
 }