**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.

);
    });
    it('should not warn for empty values', function() {
      typeCheckPass(PropTypes.shape({}), undefined);
      typeCheckPass(PropTypes.shape({}), null);
      typeCheckPass(PropTypes.shape({}), {});
    });
    it('should not warn for an empty object', function() {
      typeCheckPass(PropTypes.shape({}).isRequired, {});
    });
    it('should not warn for non specified types', function() {
      typeCheckPass(PropTypes.shape({}), {key: 1});
    });
    it('should not warn for valid types', function() {
      typeCheckPass(PropTypes.shape({key: PropTypes.number}), {key: 1});
    });
    it('should warn for required valid types', function() {
      typeCheckFail(
        PropTypes.shape({key: PropTypes.number.isRequired}),
        {},
        'Required prop `testProp.key` was not specified in `testComponent`.'
      );
    });
    it('should warn for the first required type', function() {
      typeCheckFail(
        PropTypes.shape({
          key: PropTypes.number.isRequired,
          secondKey: PropTypes.number.isRequired,
        }),
        {},