**Do you want to request a _feature_ or report a _bug_?**
Enhancement

**What is the current behavior?**
Element type checker is not as informative as the other ones.

**What is the expected behavior?**
It would be nice to provide the actual type of the prop passed similarly to other type checkers. I.e., instead of 

> Invalid prop `Prop` supplied to `Component`, expected a single ReactElement.

say

> Invalid prop `Prop` of type `type` supplied to `Component`, expected a single ReactElement.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
Seeing this on 15.2.1 but I think it's also applicable to previous versions.

I know the general intention is to move away from prop types, but if there isn't a specific reason for the current behavior I can look into making this more pretty.

k5: undefined,
      }));
      expect(console.error.calls.count()).toBe(0);
    });
    it('should not warn for iterables', function() {
      var iterable = {
        '@@iterator': function() {
          var i = 0;
          return {
            next: function() {
              var done = ++i > 2;
              return {value: done ? undefined : <MyComponent />, done: done};
            },
          };
        },
      };
      typeCheckPass(PropTypes.node, iterable);
    });
    it('should not warn for entry iterables', function() {
      var iterable = {
        '@@iterator': function() {
          var i = 0;
          return {
            next: function() {
              var done = ++i > 2;
              return {value: done ? undefined : ['#' + i, <MyComponent />], done: done};
            },
          };
        },
      };