Remove the redundant struct AnimatingData

Change-Id: Ib59636f289e7bf0ef90a9e1120b729c04ef98ccd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1939247Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Navid Zolghadr <nzolghadr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719520}

third_party/blink/renderer/core/paint/compositing/composited_layer_mapping.cc

@@ -1302,15 +1302,6 @@ static void ApplyToGraphicsLayers(const CompositedLayerMapping* mapping,
     f(mapping->DecorationOutlineLayer());
 }
 
-struct AnimatingData {
-  STACK_ALLOCATED();
-
- public:
-  Persistent<Node> owning_node = nullptr;
-  Persistent<Element> animating_element = nullptr;
-  const ComputedStyle* animating_style = nullptr;
-};
-
 // You receive an element id if you have an animation, or you're a scroller (and
 // might impl animate).
 //