Golden tests failing on CI

[shihaohong]

Describe the bug
In #437 and #409, even though both PRs update the goldens to "what it should be", they are still failing on the CI. Even weirder still, #409 should contain no UI changes since it simply adds state restoration to some of the gallery demos.

Edit: I also checked to see if it was because I ran the script with an older version of Flutter, but after updating to the latest master flutter/flutter, the failure still persists.

Flutter doctor

/Users/shihaohong/dev/apps/gallery % flutter doctor -v                                    
[✓] Flutter (Channel master, 1.27.0-5.0.pre.94, on macOS 11.2.1 20D74 darwin-x64, locale en)
    • Flutter version 1.27.0-5.0.pre.94 at /Users/shihaohong/dev/flutter
    • Framework revision 5642bed237 (8 hours ago), 2021-02-21 21:41:03 -0500
    • Engine revision b793775d2a
    • Dart version 2.13.0 (build 2.13.0-52.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
    • Android SDK at /Users/shihaohong/Library/Android/sdk
    • Platform android-30, build-tools 30.0.2
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.3, Build version 12C33
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio
    • Android Studio at /Applications/Android Studio with Blaze.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 11.0.8+10-b944.6916264)

[✓] Android Studio (version 3.5)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 38.2.3
    • Dart plugin version 191.8369
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)

[✓] VS Code (version 1.53.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.19.0

[guidezpl]

I don't remember it changing recently. Looks like a font issue (e.g. https:/flutter/gallery/pull/437/checks?check_run_id=1950907219):

test	master	diff	masked diff

cc @rami-a

[shihaohong]

I ran an empty commit (#440), and it seems to cause failure. Here is one of the diffs, which doesn't seem to look like a font issue:

[shihaohong]

I also tried to update the GitHub bot to use Big Sur as an experiment, but its only in preview so it will not actually run: #439

[guidezpl]

Strange, it looks like the test image is a low-res version