featuresフォルダに入ってるんだけどこれらは大丈夫なんだよね
C:\Program Files\Mozilla Firefox\browser\features
activity-stream@mozilla.org.xpi
aushelper@mozilla.org.xpi
e10srollout@mozilla.org.xpi
firefox@getpocket.com.xpi
followonsearch@mozilla.com.xpi
formautofill@mozilla.org.xpi
onboarding@mozilla.org.xpi
screenshots@mozilla.org.xpi
shield-recipe-client@mozilla.org.xpi
webcompat@mozilla.org.xpi