Some issues in dccd

[vicb]

this code has some issues:

• hashCode is a property of Objects in Dart - not sure if it's applicables to JS,
• not all modes have _MODE_NAMES (10, 11)

[caitp]

Thanks @vicb

[caitp]

@EisenbergEffect I think I mentioned this before, but the NOTIFIED and NOT_NOTIFIED modes are more like boolean flags, these probably shouldn't live in mode, but I don't think this ever was justified. Anyways, I'm not going to add names for them right now, but that should probably be cleaned up or at least explained more clearly.