Support for ES6 Map

[zalmoxisus]

The current implementation supports only object-like maps. The problem is that we can have any data type as a map key.

So, the following example would just throw:

new Map([
  ['a', 1],
  [{toString: function(){ return 'a' }}, 2],
  [{}, 3]
])

While with this pr, it will show the following:

Showing maps as an array of tuples was suggested in a productpains ticket.

[zalmoxisus]

We could later also add a preview in the inspector like in Chrome DevTools:

I guess here instead of indexes, we'll better use also key / value:

[zalmoxisus]

Alright. Now we'll show the preview as following:

And expanded:

I guess it's pretty good to go.

[alexkuz]

@zalmoxisus I've implemented that in latest version, so I'm gonna close this PR.
My implementation is a bit inconsistent though - it treats string/number and object keys differently, but I think Maps rarely mix primitive and object keys together:

[zalmoxisus]

@alexkuz thanks for implementing this!

Looks great! At first I had difficulties to get what entry 2 stands for, but agree that usually primitives aren't mixed. 👍

[alexkuz]

yes, there will be also an update for inspector soon.

[alexkuz]

@zalmoxisus you can try v0.11.3 now.

[zalmoxisus]

@alexkuz awesome! Thanks!