ci: disable gpu compositing

appveyor.yml

@@ -210,7 +210,7 @@ test_script:
       }
   - cd electron
   # CalculateNativeWinOcclusion is disabled due to https://bugs.chromium.org/p/chromium/issues/detail?id=1139022
-  - if "%RUN_TESTS%"=="true" ( echo Running test suite & node script/yarn test -- --trace-uncaught --enable-logging=file --log-file=%cd%\electron.log --disable-features=CalculateNativeWinOcclusion )
+  - if "%RUN_TESTS%"=="true" ( echo Running test suite & node script/yarn test -- --trace-uncaught --enable-logging=file --log-file=%cd%\electron.log --disable-features=CalculateNativeWinOcclusion --disable-gpu-compositing )
   - cd ..
   - if "%RUN_TESTS%"=="true" ( echo Verifying non proprietary ffmpeg & python electron\script\verify-ffmpeg.py --build-dir out\Default --source-root %cd% --ffmpeg-path out\ffmpeg )
   - echo "About to verify mksnapshot"