**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.string.isRequired, undefined, requiredMessage);
    });
    it('should warn if called manually in development', function() {
      spyOn(console, 'error');
      expectWarningInDevelopment(PropTypes.array, /please/);
      expectWarningInDevelopment(PropTypes.array, []);
      expectWarningInDevelopment(PropTypes.array.isRequired, /please/);
      expectWarningInDevelopment(PropTypes.array.isRequired, []);
      expectWarningInDevelopment(PropTypes.array.isRequired, null);
      expectWarningInDevelopment(PropTypes.array.isRequired, undefined);
      expectWarningInDevelopment(PropTypes.bool, []);
      expectWarningInDevelopment(PropTypes.bool, true);
      expectWarningInDevelopment(PropTypes.bool.isRequired, []);
      expectWarningInDevelopment(PropTypes.bool.isRequired, true);
      expectWarningInDevelopment(PropTypes.bool.isRequired, null);
      expectWarningInDevelopment(PropTypes.bool.isRequired, undefined);
      expectWarningInDevelopment(PropTypes.func, false);
      expectWarningInDevelopment(PropTypes.func, function() {});
      expectWarningInDevelopment(PropTypes.func.isRequired, false);
      expectWarningInDevelopment(PropTypes.func.isRequired, function() {});
      expectWarningInDevelopment(PropTypes.func.isRequired, null);
      expectWarningInDevelopment(PropTypes.func.isRequired, undefined);
      expectWarningInDevelopment(PropTypes.number, function() {});
      expectWarningInDevelopment(PropTypes.number, 42);
      expectWarningInDevelopment(PropTypes.number.isRequired, function() {});
      expectWarningInDevelopment(PropTypes.number.isRequired, 42);
      expectWarningInDevelopment(PropTypes.number.isRequired, null);
      expectWarningInDevelopment(PropTypes.number.isRequired, undefined);
      expectWarningInDevelopment(PropTypes.string, 0);
      expectWarningInDevelopment(PropTypes.string, 'foo');