**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 warn if called manually in development', function() {
      spyOn(console, 'error');
      expectWarningInDevelopment(PropTypes.shape({}), 'some string');
      expectWarningInDevelopment(PropTypes.shape({ foo: PropTypes.number }), { foo: 42 });
      expectWarningInDevelopment(
        PropTypes.shape({key: PropTypes.number}).isRequired,
        null
      );
      expectWarningInDevelopment(
        PropTypes.shape({key: PropTypes.number}).isRequired,
        undefined
      );
      expectWarningInDevelopment(PropTypes.element, <div />);
    });
  });
  describe('Symbol Type', function() {
    it('should warn for non-symbol', function() {
      typeCheckFail(
        PropTypes.symbol,
        'hello',
        'Invalid prop `testProp` of type `string` supplied to ' +
        '`testComponent`, expected `symbol`.'
      );
      typeCheckFail(
        PropTypes.symbol,
        function() { },
        'Invalid prop `testProp` of type `function` supplied to ' +
        '`testComponent`, expected `symbol`.'
      );
      typeCheckFail(