--- a/devtools/server/actors/animation.js
+++ b/devtools/server/actors/animation.js
@@ -613,30 +613,25 @@ exports.AnimationsActor = protocol.Actor
 
     this.onWillNavigate = this.onWillNavigate.bind(this);
     this.onNavigate = this.onNavigate.bind(this);
     this.onAnimationMutation = this.onAnimationMutation.bind(this);
 
     this.allAnimationsPaused = false;
     this.targetActor.on("will-navigate", this.onWillNavigate);
     this.targetActor.on("navigate", this.onNavigate);
-
-    this.animationCreatedTimeMap = new Map();
   },
 
   destroy: function() {
     Actor.prototype.destroy.call(this);
     this.targetActor.off("will-navigate", this.onWillNavigate);
     this.targetActor.off("navigate", this.onNavigate);
 
     this.stopAnimationPlayerUpdates();
     this.targetActor = this.observer = this.actors = this.walker = null;
-
-    this.animationCreatedTimeMap.clear();
-    this.animationCreatedTimeMap = null;
   },
 
   /**
    * Clients can optionally call this with a reference to their WalkerActor.
    * If they do, then AnimationPlayerActor's forms are going to also include
    * NodeActor IDs when the corresponding NodeActors do exist.
    * This, in turns, is helpful for clients to avoid having to go back once more
    * to the server to get a NodeActor for a particular animation.
@@ -652,18 +647,16 @@ exports.AnimationsActor = protocol.Actor
    * Note that calling this method a second time will destroy all previously
    * retrieved AnimationPlayerActors. Indeed, the lifecycle of these actors
    * is managed here on the server and tied to getAnimationPlayersForNode
    * being called.
    * @param {NodeActor} nodeActor The NodeActor as defined in
    * /devtools/server/actors/inspector
    */
   getAnimationPlayersForNode: function(nodeActor) {
-    this.updateAllAnimationsCreatedTime();
-
     const animations = nodeActor.rawNode.getAnimations({subtree: true});
 
     // Destroy previously stored actors
     if (this.actors) {
       for (const actor of this.actors) {
         actor.destroy();
       }
     }
@@ -742,17 +735,16 @@ exports.AnimationsActor = protocol.Actor
         if (index !== -1) {
           eventData.push({
             type: "removed",
             player: this.actors[index]
           });
           this.actors.splice(index, 1);
         }
 
-        this.updateAnimationCreatedTime(player);
         const createdTime = this.getCreatedTime(player);
         const actor = AnimationPlayerActor(this, player, createdTime);
         this.actors.push(actor);
         eventData.push({
           type: "added",
           player: actor
         });
         readyPromises.push(player.ready);
@@ -960,49 +952,18 @@ exports.AnimationsActor = protocol.Actor
   },
 
   /**
    * Return created fime of given animaiton.
    *
    * @param {Object} animation
    */
   getCreatedTime(animation) {
-    return this.animationCreatedTimeMap.get(animation);
-  },
-
-  /**
-   * Update all animation created time map.
-   */
-  updateAllAnimationsCreatedTime() {
-    const currentAnimations = this.getAllAnimations(this.targetActor.window.document);
-
-    // Remove invalid animations.
-    for (const previousAnimation of this.animationCreatedTimeMap.keys()) {
-      if (!currentAnimations.includes(previousAnimation)) {
-        this.animationCreatedTimeMap.delete(previousAnimation);
-      }
-    }
-
-    for (const animation of currentAnimations) {
-      this.updateAnimationCreatedTime(animation);
-    }
-  },
-
-  /**
-   * Update animation created time map.
-   *
-   * @param {Object} animation
-   */
-  updateAnimationCreatedTime(animation) {
-    if (!this.animationCreatedTimeMap.has(animation)) {
-      const createdTime =
-        animation.startTime ||
-        animation.timeline.currentTime - animation.currentTime / animation.playbackRate;
-      this.animationCreatedTimeMap.set(animation, createdTime);
-    }
+    return animation.startTime ||
+          animation.timeline.currentTime - animation.currentTime / animation.playbackRate;
   },
 
   /**
    * Wait for next animation frame.
    *
    * @param {Array} actors
    * @return {Promise} which waits for next frame
    */