Security bump for uglifier
Security bump for uglifier

Fixes https://github.com/mishoo/UglifyJS2/issues/751

bitzesty/trade-tariff-admin,alphagov/trade-tariff-admin,bitzesty/trade-tariff-admin,alphagov/trade-tariff-admin,bitzesty/trade-tariff-admin,alphagov/trade-tariff-admin,bitzesty/trade-tariff-admin,alphagov/trade-tariff-admin