--- a/dom/animation/Animation.cpp
+++ b/dom/animation/Animation.cpp
@@ -1021,19 +1021,18 @@ Animation::WillComposeStyle()
   MOZ_ASSERT(mEffect);
 
   KeyframeEffectReadOnly* keyframeEffect = mEffect->AsKeyframeEffect();
   if (keyframeEffect) {
     keyframeEffect->WillComposeStyle();
   }
 }
 
-template<typename ComposeAnimationResult>
 void
-Animation::ComposeStyle(ComposeAnimationResult&& aComposeResult,
+Animation::ComposeStyle(RawServoAnimationValueMap& aComposeResult,
                         const nsCSSPropertyIDSet& aPropertiesToSkip)
 {
   if (!mEffect) {
     return;
   }
 
   // In order to prevent flicker, there are a few cases where we want to use
   // a different time for rendering that would otherwise be returned by
@@ -1083,18 +1082,17 @@ Animation::ComposeStyle(ComposeAnimation
       if (!timeToUse.IsNull()) {
         mHoldTime = CurrentTimeFromTimelineTime(
           timeToUse.Value(), mStartTime.Value(), mPlaybackRate);
       }
     }
 
     KeyframeEffectReadOnly* keyframeEffect = mEffect->AsKeyframeEffect();
     if (keyframeEffect) {
-      keyframeEffect->ComposeStyle(Forward<ComposeAnimationResult>(aComposeResult),
-                                   aPropertiesToSkip);
+      keyframeEffect->ComposeStyle(aComposeResult, aPropertiesToSkip);
     }
   }
 
   MOZ_ASSERT(pending == Pending(),
              "Pending state should not change during the course of compositing");
 }
 
 void
@@ -1653,16 +1651,10 @@ bool
 Animation::IsRunningOnCompositor() const
 {
   return mEffect &&
          mEffect->AsKeyframeEffect() &&
          mEffect->AsKeyframeEffect()->IsRunningOnCompositor();
 }
 
 
-template
-void
-Animation::ComposeStyle<RawServoAnimationValueMap&>(
-  RawServoAnimationValueMap& aAnimationValues,
-  const nsCSSPropertyIDSet& aPropertiesToSkip);
-
 } // namespace dom
 } // namespace mozilla

--- a/dom/animation/Animation.h
+++ b/dom/animation/Animation.h
@@ -368,18 +368,17 @@ public:
   void WillComposeStyle();
 
   /**
    * Updates |aComposeResult| with the animation values of this animation's
    * effect, if any.
    * Any properties contained in |aPropertiesToSkip| will not be added or
    * updated in |aComposeResult|.
    */
-  template<typename ComposeAnimationResult>
-  void ComposeStyle(ComposeAnimationResult&& aComposeResult,
+  void ComposeStyle(RawServoAnimationValueMap& aComposeResult,
                     const nsCSSPropertyIDSet& aPropertiesToSkip);
 
   void NotifyEffectTimingUpdated();
   void NotifyGeometricAnimationsStartingThisFrame();
 
   /**
    * Used by subclasses to synchronously queue a cancel event in situations
    * where the Animation may have been cancelled.

--- a/dom/animation/KeyframeEffectReadOnly.cpp
+++ b/dom/animation/KeyframeEffectReadOnly.cpp
@@ -416,20 +416,19 @@ KeyframeEffectReadOnly::ComposeStyleRule
                          &mBaseStyleValuesForServo,
                          aProperty.mProperty,
                          &aSegment,
                          &aProperty.mSegments.LastElement(),
                          &aComputedTiming,
                          mEffectOptions.mIterationComposite);
 }
 
-template<typename ComposeAnimationResult>
 void
 KeyframeEffectReadOnly::ComposeStyle(
-  ComposeAnimationResult&& aComposeResult,
+  RawServoAnimationValueMap& aComposeResult,
   const nsCSSPropertyIDSet& aPropertiesToSkip)
 {
   MOZ_DIAGNOSTIC_ASSERT(!mIsComposingStyle,
                         "Should not be called recursively");
   if (mIsComposingStyle) {
     return;
   }
 
@@ -472,20 +471,17 @@ KeyframeEffectReadOnly::ComposeStyle(
       MOZ_ASSERT(segment->mFromKey == (segment-1)->mToKey, "incorrect keys");
     }
     MOZ_ASSERT(segment->mFromKey <= segment->mToKey, "incorrect keys");
     MOZ_ASSERT(segment >= prop.mSegments.Elements() &&
                size_t(segment - prop.mSegments.Elements()) <
                  prop.mSegments.Length(),
                "out of array bounds");
 
-    ComposeStyleRule(Forward<ComposeAnimationResult>(aComposeResult),
-                     prop,
-                     *segment,
-                     computedTiming);
+    ComposeStyleRule(aComposeResult, prop, *segment, computedTiming);
   }
 
   // If the animation produces a transform change hint that affects the overflow
   // region, we need to record the current time to unthrottle the animation
   // periodically when the animation is being throttled because it's scrolled
   // out of view.
   if (HasTransformThatMightAffectOverflow()) {
     nsPresContext* presContext =
@@ -1695,16 +1691,10 @@ KeyframeEffectReadOnly::UpdateEffectSet(
     effectSet->SetMayHaveTransformAnimation();
     if (frame) {
       frame->SetMayHaveTransformAnimation();
     }
   }
 }
 
 
-template
-void
-KeyframeEffectReadOnly::ComposeStyle<RawServoAnimationValueMap&>(
-  RawServoAnimationValueMap& aAnimationValues,
-  const nsCSSPropertyIDSet& aPropertiesToSkip);
-
 } // namespace dom
 } // namespace mozilla

--- a/dom/animation/KeyframeEffectReadOnly.h
+++ b/dom/animation/KeyframeEffectReadOnly.h
@@ -199,18 +199,17 @@ public:
   // We need to update this outside ComposeStyle() because we should avoid
   // mutating any state in ComposeStyle() since it might be called during
   // parallel traversal.
   void WillComposeStyle();
 
   // Updates |aComposeResult| with the animation values produced by this
   // AnimationEffect for the current time except any properties contained
   // in |aPropertiesToSkip|.
-  template<typename ComposeAnimationResult>
-  void ComposeStyle(ComposeAnimationResult&& aRestultContainer,
+  void ComposeStyle(RawServoAnimationValueMap& aComposeResult,
                     const nsCSSPropertyIDSet& aPropertiesToSkip);
 
 
   // Returns true if at least one property is being animated on compositor.
   bool IsRunningOnCompositor() const;
   void SetIsRunningOnCompositor(nsCSSPropertyID aProperty, bool aIsRunning);
   void ResetIsRunningOnCompositor();