hotfix

FIXES IE11 exception in broken array-copy wrapper (error message: "Function.prototype.call: 'this' is not a Function object)

We attempted to use the recommended technique where available to do shallow copy operations on Array-like types (assuming Array.from where available would be better). All recent browsers are implementing the Array.from method, why we noticed this bug too late. The way we were calling Array.prototype.slice on IE11 was ineffective: our compatiblity-wrapper function was crafted in the wrong manner - as we have learned in a painful way.

See #1786

Our main take-away here is improving our CI acceptance testing in browser VMs, so we can have confident automated testing on IE11 as well, and notice such issues before we merge them

Also, we have now actually acknowledged that slice is usually more performant, which might be because of Array.from supporting a more wide range of parameters: https://jsperf.com/array-from-vs-array-prototype-slice