Update babel7 to the latest version 🚀 (#1074)

* chore(package): update @babel/core to version 7.8.4

* chore(package): update @babel/plugin-proposal-class-properties to version 7.8.3

* chore(package): update @babel/plugin-transform-flow-comments to version 7.8.3

* chore(package): update @babel/plugin-transform-flow-strip-types to version 7.8.3

* chore(package): update @babel/plugin-transform-runtime to version 7.8.3

* chore(package): update @babel/preset-env to version 7.8.4

* chore(package): update @babel/preset-react to version 7.8.3

* fix(package): update @babel/runtime to version 7.8.4

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]