React 0.14.7: `<option value="">empty</option>` emits empty string on change
http://jsbin.com/pisita/10/edit?html,js,console,output
React 15.0.0-rc.1`<option value="">empty</option>` emits string with value "empty" on change
http://jsbin.com/bemaze/12/edit?html,js,console,output
This is because React 15.0.0-rc.1 cuts off `value=""` from option tag

if (this._rootNodeID) {
    
    ReactDOMTextarea.updateWrapper(this);
  }
}
function warnIfValueIsNull(props) {
  if (props != null && props.value === null && !didWarnValueNull) {
    warning(
      false,
      '`value` prop on `textarea` should not be null. ' +
      'Consider using the empty string to clear the component or `undefined` ' +
      'for uncontrolled components.'
    );
    didWarnValueNull = true;
  }
}
/**
 * Implements a <textarea> host component that allows setting `value`, and
 * `defaultValue`. This differs from the traditional DOM API because value is
 * usually set as PCDATA children.
 *