Add iOS spring animation objc files

ci/licenses_golden/licenses_flutter

@@ -714,9 +714,11 @@ SOFTWARE.
 
 ====================================================================================================
 LIBRARY: spring_animation
-ORIGIN: ../../../flutter/third_party/spring_animation/Libraries/Animated/animations/SpringAnimation.js + ../../../flutter/third_party/spring_animation/LICENSE
+ORIGIN: ../../../flutter/third_party/spring_animation/spring_animation.h + ../../../flutter/third_party/spring_animation/LICENSE
+ORIGIN: ../../../flutter/third_party/spring_animation/spring_animation.mm + ../../../flutter/third_party/spring_animation/LICENSE
 TYPE: LicenseType.mit
-FILE: ../../../flutter/third_party/spring_animation/Libraries/Animated/animations/SpringAnimation.js
+FILE: ../../../flutter/third_party/spring_animation/spring_animation.h
+FILE: ../../../flutter/third_party/spring_animation/spring_animation.mm
 ----------------------------------------------------------------------------------------------------
 Copyright (c) Meta Platforms, Inc. and affiliates.
 

third_party/spring_animation/BUILD.gn

@@ -0,0 +1,14 @@
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+if (is_ios) {
+  import("//flutter/common/config.gni")
+  source_set("spring_animation") {
+    sources = [
+      "spring_animation.h",
+      "spring_animation.mm",
+    ]
+    public_configs = [ "//flutter:config" ]
+  }
+}