Fix input text color on dark GTK themes (fix mozilla/addons#657)
Fix input text color on dark GTK themes (fix mozilla/addons#657)

kumar303/addons-frontend,kumar303/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,kumar303/addons-frontend,tsl143/addons-frontend,mozilla/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,tsl143/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,tsl143/addons-frontend,kumar303/addons-frontend,tsl143/addons-frontend,mozilla/addons-frontend,mozilla/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,mozilla/addons-frontend