**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.

var propType = getPropType(propValue);
  if (propType === 'object') {
    if (propValue instanceof Date) {
      return 'date';
    } else if (propValue instanceof RegExp) {
      return 'regexp';
    }
  }
  return propType;
}
function getClassName(propValue) {
  if (!propValue.constructor || !propValue.constructor.name) {
    return ANONYMOUS;
  }
  return propValue.constructor.name;
}
module.exports = ReactPropTypes;