--- a/layout/style/ServoBindingTypes.h
+++ b/layout/style/ServoBindingTypes.h
@@ -20,31 +20,33 @@ struct RawServoStyleSet;
 #undef SERVO_ARC_TYPE
 
 namespace mozilla {
   class ServoElementSnapshot;
 namespace dom {
 class Element;
 class StyleChildrenIterator;
 } // namespace dom
+struct Keyframe;
 struct PropertyStyleAnimationValuePair;
 } // namespace mozilla
 
 class nsCSSValue;
 class nsIDocument;
 class nsINode;
 class nsPresContext;
 
 using mozilla::dom::StyleChildrenIterator;
 using mozilla::ServoElementSnapshot;
 
 typedef nsINode RawGeckoNode;
 typedef mozilla::dom::Element RawGeckoElement;
 typedef nsIDocument RawGeckoDocument;
 typedef nsPresContext RawGeckoPresContext;
+typedef nsTArray<mozilla::Keyframe> RawGeckoKeyframeList;
 typedef nsTArray<mozilla::PropertyStyleAnimationValuePair> RawGeckoAnimationValueList;
 typedef nsTArray<const RawServoAnimationValue*> RawServoAnimationValueBorrowedList;
 
 // We have these helper types so that we can directly generate
 // things like &T or Borrowed<T> on the Rust side in the function, providing
 // additional safety benefits.
 //
 // FFI has a problem with templated types, so we just use raw pointers here.
@@ -107,16 +109,17 @@ DECL_NULLABLE_BORROWED_REF_TYPE_FOR(RawG
 DECL_BORROWED_MUT_REF_TYPE_FOR(StyleChildrenIterator)
 DECL_BORROWED_MUT_REF_TYPE_FOR(ServoElementSnapshot)
 DECL_BORROWED_REF_TYPE_FOR(nsCSSValue)
 DECL_BORROWED_MUT_REF_TYPE_FOR(nsCSSValue)
 DECL_OWNED_REF_TYPE_FOR(RawGeckoPresContext)
 DECL_BORROWED_REF_TYPE_FOR(RawGeckoPresContext)
 DECL_BORROWED_MUT_REF_TYPE_FOR(RawGeckoAnimationValueList)
 DECL_BORROWED_REF_TYPE_FOR(RawServoAnimationValueBorrowedList)
+DECL_BORROWED_MUT_REF_TYPE_FOR(RawGeckoKeyframeList)
 
 #undef DECL_ARC_REF_TYPE_FOR
 #undef DECL_OWNED_REF_TYPE_FOR
 #undef DECL_NULLABLE_OWNED_REF_TYPE_FOR
 #undef DECL_BORROWED_REF_TYPE_FOR
 #undef DECL_NULLABLE_BORROWED_REF_TYPE_FOR
 #undef DECL_BORROWED_MUT_REF_TYPE_FOR
 #undef DECL_NULLABLE_BORROWED_MUT_REF_TYPE_FOR

--- a/layout/style/ServoBindingTypes.h.rej
+++ b/layout/style/ServoBindingTypes.h.rej
@@ -1,38 +1,10 @@
 --- ServoBindingTypes.h
 +++ ServoBindingTypes.h
-@@ -36,16 +36,17 @@ class nsPresContext;
- using mozilla::dom::StyleChildrenIterator;
- using mozilla::ServoElementSnapshot;
- 
- typedef nsINode RawGeckoNode;
- typedef mozilla::dom::Element RawGeckoElement;
- typedef nsIDocument RawGeckoDocument;
- typedef nsPresContext RawGeckoPresContext;
- typedef nsTArray<mozilla::PropertyStyleAnimationValuePair> RawGeckoAnimationValueList;
-+typedef nsTArray<const RawServoAnimationValue*> RawServoAnimationValueBorrowedList;
- 
- // We have these helper types so that we can directly generate
- // things like &T or Borrowed<T> on the Rust side in the function, providing
- // additional safety benefits.
- //
- // FFI has a problem with templated types, so we just use raw pointers here.
- //
- // The "Borrowed" types generate &T or Borrowed<T> in the nullable case.
-@@ -105,16 +106,17 @@ DECL_BORROWED_REF_TYPE_FOR(RawGeckoDocum
- DECL_NULLABLE_BORROWED_REF_TYPE_FOR(RawGeckoDocument)
- DECL_BORROWED_MUT_REF_TYPE_FOR(StyleChildrenIterator)
- DECL_BORROWED_MUT_REF_TYPE_FOR(ServoElementSnapshot)
- DECL_BORROWED_REF_TYPE_FOR(nsCSSValue)
- DECL_BORROWED_MUT_REF_TYPE_FOR(nsCSSValue)
+@@ -110,6 +112,7 @@ DECL_BORROWED_MUT_REF_TYPE_FOR(nsCSSValu
  DECL_OWNED_REF_TYPE_FOR(RawGeckoPresContext)
  DECL_BORROWED_REF_TYPE_FOR(RawGeckoPresContext)
  DECL_BORROWED_MUT_REF_TYPE_FOR(RawGeckoAnimationValueList)
-+DECL_BORROWED_REF_TYPE_FOR(RawServoAnimationValueBorrowedList)
++DECL_BORROWED_MUT_REF_TYPE_FOR(RawGeckoKeyframeList)
  
  #undef DECL_ARC_REF_TYPE_FOR
  #undef DECL_OWNED_REF_TYPE_FOR
- #undef DECL_NULLABLE_OWNED_REF_TYPE_FOR
- #undef DECL_BORROWED_REF_TYPE_FOR
- #undef DECL_NULLABLE_BORROWED_REF_TYPE_FOR
- #undef DECL_BORROWED_MUT_REF_TYPE_FOR
- #undef DECL_NULLABLE_BORROWED_MUT_REF_TYPE_FOR

--- a/layout/style/ServoBindings.cpp
+++ b/layout/style/ServoBindings.cpp
@@ -27,16 +27,17 @@
 #include "nsRuleNode.h"
 #include "nsString.h"
 #include "nsStyleStruct.h"
 #include "nsStyleUtil.h"
 #include "nsTArray.h"
 
 #include "mozilla/EffectCompositor.h"
 #include "mozilla/EventStates.h"
+#include "mozilla/Keyframe.h"
 #include "mozilla/ServoAnimationRule.h"
 #include "mozilla/ServoElementSnapshot.h"
 #include "mozilla/ServoRestyleManager.h"
 #include "mozilla/StyleAnimationValue.h"
 #include "mozilla/DeclarationBlockInlines.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/ElementInlines.h"
 
@@ -942,16 +943,32 @@ void
 Gecko_EnsureStyleAnimationArrayLength(void* aArray, size_t aLen)
 {
   auto base =
     reinterpret_cast<nsStyleAutoArray<StyleAnimation>*>(aArray);
 
   base->EnsureLengthAtLeast(aLen);
 }
 
+Keyframe*
+Gecko_AnimationAppendKeyframe(RawGeckoKeyframeListBorrowedMut aKeyframes,
+                              float aOffset,
+                              const nsTimingFunction* aTimingFunction)
+{
+  Keyframe* keyframe = aKeyframes->AppendElement();
+  keyframe->mOffset.emplace(aOffset);
+  if (aTimingFunction &&
+      aTimingFunction->mType != nsTimingFunction::Type::Linear) {
+    keyframe->mTimingFunction.emplace();
+    keyframe->mTimingFunction->Init(*aTimingFunction);
+  }
+
+  return keyframe;
+}
+
 void
 Gecko_ResetStyleCoord(nsStyleUnit* aUnit, nsStyleUnion* aValue)
 {
   nsStyleCoord::Reset(*aUnit, *aValue);
 }
 
 void
 Gecko_SetStyleCoordCalcValue(nsStyleUnit* aUnit, nsStyleUnion* aValue, nsStyleCoord::CalcValue aCalc)

--- a/layout/style/ServoBindings.cpp.rej
+++ b/layout/style/ServoBindings.cpp.rej
@@ -1,22 +1,10 @@
 --- ServoBindings.cpp
 +++ ServoBindings.cpp
-@@ -24,17 +25,19 @@
- #include "nsNameSpaceManager.h"
- #include "nsNetUtil.h"
- #include "nsRuleNode.h"
- #include "nsString.h"
- #include "nsStyleStruct.h"
- #include "nsStyleUtil.h"
+@@ -30,6 +30,7 @@
  #include "nsTArray.h"
  
-+#include "mozilla/EffectCompositor.h"
  #include "mozilla/EventStates.h"
-+#include "mozilla/ServoAnimationRule.h"
++#include "mozilla/Keyframe.h"
  #include "mozilla/ServoElementSnapshot.h"
  #include "mozilla/ServoRestyleManager.h"
  #include "mozilla/StyleAnimationValue.h"
- #include "mozilla/DeclarationBlockInlines.h"
- #include "mozilla/dom/Element.h"
- #include "mozilla/dom/ElementInlines.h"
- 
- using namespace mozilla;

--- a/layout/style/ServoBindings.h
+++ b/layout/style/ServoBindings.h
@@ -29,16 +29,17 @@
 class nsIAtom;
 class nsIPrincipal;
 class nsIURI;
 struct nsFont;
 namespace mozilla {
   class ServoStyleSheet;
   class FontFamilyList;
   enum FontFamilyType : uint32_t;
+  struct Keyframe;
 }
 using mozilla::FontFamilyList;
 using mozilla::FontFamilyType;
 using mozilla::ServoElementSnapshot;
 struct nsMediaFeature;
 struct nsStyleList;
 struct nsStyleImage;
 struct nsStyleGradientStop;
@@ -262,16 +263,20 @@ void Gecko_ClearPODTArray(void* array, s
 void Gecko_ClearStyleContents(nsStyleContent* content);
 void Gecko_CopyStyleContentsFrom(nsStyleContent* content, const nsStyleContent* other);
 
 void Gecko_EnsureImageLayersLength(nsStyleImageLayers* layers, size_t len,
                                    nsStyleImageLayers::LayerType layer_type);
 
 void Gecko_EnsureStyleAnimationArrayLength(void* array, size_t len);
 
+mozilla::Keyframe* Gecko_AnimationAppendKeyframe(RawGeckoKeyframeListBorrowedMut keyframes,
+                                                 float offset,
+                                                 const nsTimingFunction* timingFunction);
+
 // Clean up pointer-based coordinates
 void Gecko_ResetStyleCoord(nsStyleUnit* unit, nsStyleUnion* value);
 
 // Set an nsStyleCoord to a computed `calc()` value
 void Gecko_SetStyleCoordCalcValue(nsStyleUnit* unit, nsStyleUnion* value, nsStyleCoord::CalcValue calc);
 
 void Gecko_CopyClipPathValueFrom(mozilla::StyleClipPath* dst, const mozilla::StyleClipPath* src);