Bug#960261: node-babel7: @babel/polyfill depends on old core-js

[Xavier Guimard]

Package: node-babel7
Version: 7.4.5-8
Severity: important
Control: affects -1 node-string-decoder

@babel/polyfill requires core-js/es6 and some other core-js files that
are not available with node-core-js ≥ 3