Manual roll of engine 45b66b7...ffba2f6 (#35464)

* Manual roll of engine 45b66b7...ffba2f6

git log 45b66b7...ffba2f6 --oneline

ffba2f68d Roll src/third_party/dart b37aa3b036...0abff7b2bb (#9588)
62514cb77 Roll fuchsia/sdk/core/mac-amd64 from n9fZpXVmsbgKZzS8Q2GXxB453q8AbLpfGztsPsq47pMC to BYCwsJf7r7zfd2THSGinFeIHv552AEVchXdc7VZzP0IC (#9587)
9f2721284 Roll src/third_party/skia e4c88bb1f848..1ddee025229a (7 commits) (#9586)
03a31e0ad Roll fuchsia/sdk/core/linux-amd64 from F9oY0d56X3aONxwv5vw9Gco--AHmC8SHuDXdhdWCnnMC to d2VK3FYSEKQ35UdZw5FdbOZUI_xgT0-1h8DnGDUHPVAC (#9583)

* Fix analyzer warning.

bin/internal/engine.version

-45b66b722e1275c47dccbe6b002c8e4cb13ea983
+ffba2f68d4e8ec2041f57226d907dcb929c8b795

packages/flutter/test/widgets/gesture_detector_semantics_test.dart

@@ -714,7 +714,7 @@ class _TestLayoutPerformer extends SingleChildRenderObjectWidget {
 class _RenderTestLayoutPerformer extends RenderBox {
   _RenderTestLayoutPerformer({VoidCallback performLayout}) : _performLayout = performLayout;
 
-  VoidCallback _performLayout;
+  final VoidCallback _performLayout;
 
   @override
   void performLayout() {