Please forgive me if this appears more like a rant than a feature request, but I have searched and can't find any explanation for why some error messages are displayed without any `displayName` from the component responsible - and this is driving me insane.

_Every_ component in my project has an explicit `displayName` specified.  I do this for debugging.

I am rendering a bunch of immutable props.  I changed one of the prop types from a `List` to a `Map` and I see:

> Warning: Using Maps as children is not yet fully supported. It is an experimental feature that might be removed. Convert it to a sequence / iterable of keyed ReactElements instead.

Obviously I missed something, which could be easily fixed if I knew _where_ it was - even just the component's name.

This message is not only frustrating, but it's taunting "I know where the problem is but I won't tell you!"-feel makes it infuriating.  Looking at the stacktrace behind it is useless as well because it's, as usual, a never-ending list of React function calls with no mention of any of my source files.

I have spent countless time hunting down errors like this that would have taken only moments if I knew the name of the component responsible.  It would be _infinitely more helpful_ if the `displayName` field appeared in more debug output.

var traverseContext = [];
    var traverseFn =
      jasmine.createSpy().and.callFake(function(context, kid, key, index) {
        context.push(true);
      });
    var instance = (
      <div>{
        [
          frag({
            firstHalfKey: [zero, one, two],
            secondHalfKey: [three, four],
            keyFive: five,
          }),
        ]
      }</div>
    );
    traverseAllChildren(instance.props.children, traverseFn, traverseContext);
    expect(traverseFn.calls.count()).toBe(4);
    expect(traverseContext.length).toEqual(4);
    expect(traverseFn).toHaveBeenCalledWith(
      traverseContext,
      <div key="firstHalfKey/.$keyZero" />,
      '.0:$firstHalfKey/.$keyZero'
    );
    expect(traverseFn).toHaveBeenCalledWith(