JavaScript implementation of balanced trees is broken in 4.1.2

[cata]

Removing the first element in a map or set yields and empty map/set.
Repro: http://try.websharper.com/snippet/0000IB

I am unsure if this is the only scenario that breaks.
Update: removing the last element has the same effect

[Tarmil]

Sorry about that, looks like our tests were insufficient.

I reverted 44fcc35 which introduced this issue: it is not needed anymore since we've changed how maps are serialized to JSON. This will be on NuGet very soon.

[Tarmil]

The fix is released on NuGet in v4.1.3.

[cata]

Thanks @Tarmil !