Add missing key attribute for <p class="stateprops"> list in ComponentMap

[aspiers]

In the ComponentMap view, the tooltip viewable after clicking on a component has a list of <p className="stateprops"> elements, but React requires that every element of a list has a key attribute to enable its DOM tracking / reconciliation.

So add the missing key attribute to avoid this warning:

react.development.js:315 Warning: Each child in a list should have a unique "key" prop.