Cannot load core-js

[ngocdaothanh]

core-js is a popular ES6 polyfill:
https://github.com/zloirock/core-js

For example, it's used in Babel:
https://babeljs.io/docs/en/babel-preset-env

I've used rollup:
https://github.com/ngocdaothanh/one-core-js

To merge all ES6 polyfill files:
https://github.com/zloirock/core-js/blob/master/packages/core-js/es/index.js

Into this one file:
https://github.com/ngocdaothanh/one-core-js/blob/master/es6polyfills.js

When esper.js loads that file, there's error:
Cant index propertyIsEnumerable of undefined

The error is thrown from here:
https://github.com/codecombat/esper.js/blob/master/src/Evaluator.js#L406

Would you please investigate and fix the error?

[basicer]

Is there any particular ES6 feature you are looking for? It might be easier to just implement that feature instead of trying to get a complicated polyfill to load.

[ngocdaothanh]

I want some basic commonly used ES6 features like Array.from.

esper.js cannot load when cherry picking Array.from from core-js:
https://github.com/zloirock/core-js/blob/master/packages/core-js/es/array/from.js

esper.js cannot load es6-shim either:
https://github.com/paulmillr/es6-shim

This simple polyfill works however:
https://gist.github.com/brettz9/4212262

It would be perfect (ES6 feature complete) if esper.js can load popular ES6 polyfills.