Manual roll the engine to land the timing API (#33989)

This will manually land https://github.com/flutter/engine/pull/8983 in
the framework.

bin/internal/engine.version

-afb9d510c3bb0f1b97980434b41200a2d3491697
+74975a4d17162f23bea92ac298d1b96c2995a529

packages/flutter_test/lib/src/window.dart

@@ -243,6 +243,13 @@ class TestWindow implements Window {
     _window.onDrawFrame = callback;
   }
 
+  @override
+  TimingsCallback get onReportTimings => _window.onReportTimings;
+  @override
+  set onReportTimings(TimingsCallback callback) {
+    _window.onReportTimings = callback;
+  }
+
   @override
   PointerDataPacketCallback get onPointerDataPacket => _window.onPointerDataPacket;
   @override