
This pull request fixes #143803 by taking advantage of Dart's null-aware operators. And unlike `switch` expressions ([9 PRs](https://github.com/flutter/flutter/pull/143634) and counting), the Flutter codebase is already fantastic when it comes to null-aware coding. After refactoring the entire repo, all the changes involving `?.` and `??` can fit into a single pull request.
microbenchmarks
To run these benchmarks on a device, first run `flutter logs' in one window to see the device logs, then, in a different window, run any of these:
flutter run --release lib/gestures/velocity_tracker_bench.dart
flutter run --release lib/gestures/gesture_detector_bench.dart
flutter run --release lib/stocks/animation_bench.dart
flutter run --release lib/stocks/build_bench.dart
flutter run --release lib/stocks/layout_bench.dart
The results should be in the device logs.
Avoid changing names of the benchmarks
Each microbenchmark is identified by a name, for example, "catmullrom_transform_iteration". Changing the name of an existing microbenchmarks will effectively remove the old benchmark and create a new one, losing the historical data associated with the old benchmark in the process.