[redux-devtools-inspector] Diff for Dates doesn't work

[zalmoxisus]

As discussed in https://github.com/zalmoxisus/redux-devtools-extension/issues/468#issuecomment-443904881, Diff tab shows no changes for Dates, except when the type is changed from/to another. According to jsondiffpatch, it should be supported.

[agalazis]

I think there is a similar issue with sets as well