Pass own props to areStatesEqual

[gawhyte]

I have often found myself wishing that a component's own props were available in the areStatesEqual method. I usually use an immutable.js store and convert to plain JS objects while mapping (which can potentially be expensive) and use areStatesEqual to prevent mapping unnecessarily. I am also sometimes using a property of the component to slice off a subsection of the state which leads me to wish I could sometimes do something like this:

connect(
    (state, props) => state[props.context].toJS(),
    null,
    null,
    {
      areStatesEqual: (nextState, prevState, nextProps, prevProps) => nextState[nextProps.context].equals(prevState[prevProps.context]),
    }
)

Does anybody else encounter/wish for this? Is there a philosophical reason this shouldn't be done? Looking at the code it appears it would be trivial to make this change. I thought it best I should check before opening a pull request.

[timdorr]

Dupe of #781