18 tests are failing in IE, Safari <= 8, iOS <= 8 and Android <= 4.4.

The root cause is that RxJS hard-codes System.iterator to _es6shim_iterator_ in these browsers. It was the token used by es6-shim, but it has been changed to _es6-shim iterator_ a year ago.

A PR has been opened to solve it on RxJS side: ReactiveX/rxjs#640
Once it is available, RxJS dependency should be updated and workarounds removed.

/cc @Blesh @robwormald