FlutterのiOSビルド時にtrack-widget-creationオプションが見つからないエラーが出る

環境情報

$ flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, v1.0.0, on Mac OS X 10.14 18A391, locale ja-JP)
[✓] Android toolchain - develop for Android devices (Android SDK 28.0.3)
[✓] iOS toolchain - develop for iOS devices (Xcode 10.1)
[✓] Android Studio (version 3.2)
[✓] IntelliJ IDEA Community Edition (version 2018.3.2)
[✓] Connected device (2 available)

問題

FlutterアプリのiOSビルドを行うと下記エラーが発生する。

$ flutter build ios --release

---
Xcode's output:
↳
    === BUILD TARGET Runner OF PROJECT Runner WITH CONFIGURATION Release ===
    Could not find an option named "track-widget-creation".

    Run 'flutter -h' (or 'flutter <command> -h') for available flutter commands and options.
    Failed to build xxx.
    Command /bin/sh failed with exit code 255

解決方法

Flutterのxcode_backend.shを編集する。
（track-widget-creationオプションを付けないようにする）
なんか根本的な解決方法になってないと思うので、CIでのビルドでコケたら追記します。

$ vi $FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh

local track_widget_creation_flag=""
if [[ -n "$TRACK_WIDGET_CREATION" ]]; then
  # track_widget_creation_flag="--track-widget-creation"
  track_widget_creation_flag=""
fi

追記：
Release.xcconfigにTRACK_WIDGET_CREATION=を追記する方が正しそうです。

$ vi $PROJECT_ROOT/ios/Flutter/Release.xcconfig

TRACK_WIDGET_CREATION=// 追記

参考

https://github.com/flutter/flutter/issues/24239
https://wapa5pow.com/flutter-ci-cd/