**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.

});
  describe('ObjectOf Type', function() {
    it('should fail for invalid argument', function() {
      typeCheckFail(
        PropTypes.objectOf({ foo: PropTypes.string }),
        { foo: 'bar' },
        'Property `testProp` of component `testComponent` has invalid PropType notation inside objectOf.'
      );
    });
    it('should support the objectOf propTypes', function() {
      typeCheckPass(PropTypes.objectOf(PropTypes.number), {a: 1, b: 2, c: 3});
      typeCheckPass(
        PropTypes.objectOf(PropTypes.string),
        {a: 'a', b: 'b', c: 'c'}
      );
      typeCheckPass(
        PropTypes.objectOf(PropTypes.oneOf(['a', 'b'])),
        {a: 'a', b: 'b'}
      );
      typeCheckPass(
        PropTypes.objectOf(PropTypes.symbol),
        {a: Symbol(), b: Symbol(), c: Symbol()}
      );
    });
    it('should support objectOf with complex types', function() {
      typeCheckPass(
        PropTypes.objectOf(PropTypes.shape({a: PropTypes.number.isRequired})),
        {a: {a: 1}, b: {a: 2}}
      );
      function Thing() {}