F# anonymous records can break `client` helper of UI

[Jand42]

See gitter thread at: https://gitter.im/intellifactory/websharper?at=6106a06172c37b6f4585c383

Workaround: use named record types for any method signatures that you intent to call from client instead.

Issue must be something about the anonymous record type being named differently during compile-time and runtime. Low priority bug, hard to reproduce, it worked for simple cases I have tested.