**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.

typeCheckFail(PropTypes.any.isRequired, null, requiredMessage);
      typeCheckFail(PropTypes.any.isRequired, undefined, requiredMessage);
    });
    it('should warn if called manually in development', function() {
      spyOn(console, 'error');
      expectWarningInDevelopment(PropTypes.any, null);
      expectWarningInDevelopment(PropTypes.any.isRequired, null);
      expectWarningInDevelopment(PropTypes.any.isRequired, undefined);
    });
  });
  describe('ArrayOf Type', function() {
    it('should fail for invalid argument', function() {
      typeCheckFail(
        PropTypes.arrayOf({ foo: PropTypes.string }),
        { foo: 'bar' },
        'Property `testProp` of component `testComponent` has invalid PropType notation inside arrayOf.'
      );
    });
    it('should support the arrayOf propTypes', function() {
      typeCheckPass(PropTypes.arrayOf(PropTypes.number), [1, 2, 3]);
      typeCheckPass(PropTypes.arrayOf(PropTypes.string), ['a', 'b', 'c']);
      typeCheckPass(PropTypes.arrayOf(PropTypes.oneOf(['a', 'b'])), ['a', 'b']);
      typeCheckPass(PropTypes.arrayOf(PropTypes.symbol), [Symbol(), Symbol()]);
    });
    it('should support arrayOf with complex types', function() {
      typeCheckPass(
        PropTypes.arrayOf(PropTypes.shape({a: PropTypes.number.isRequired})),
        [{a: 1}, {a: 2}]
      );
      function Thing() {}