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

'impossible to unmount some top-level components (eg <html>, ' +
          '<head>, and <body>) reliably and efficiently. To fix this, have a ' +
          'single top-level component that never unmounts render these ' +
          'elements.',
          this._tag
        );
        break;
    }
    this.unmountChildren(safely);
    ReactDOMComponentTree.uncacheNode(this);
    EventPluginHub.deleteAllListeners(this);
    ReactComponentBrowserEnvironment.unmountIDFromEnvironment(this._rootNodeID);
    this._rootNodeID = null;
    this._domID = null;
    this._wrapperState = null;
    if (__DEV__) {
      setContentChildForInstrumentation.call(this, null);
    }
  },
  getPublicInstance: function() {
    return getNode(this);
  },
};
Object.assign(
  ReactDOMComponent.prototype,
  ReactDOMComponent.Mixin,
  ReactMultiChild.Mixin
);
module.exports = ReactDOMComponent;