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**Do you want to request a *feature* or report a *bug*?**

Bug? Mild DX improvement.

**What is the current behavior?**

Creating an input with an undefined or null value, then later passing a string value, triggers a warning about controlled inputs.

> A component is changing an uncontrolled input of type undefined to be controlled. Input elements should not switch from uncontrolled to controlled (or vice versa)

It's my experience in Reactiflux that this warning is unclear to developers with less familiarity with React, or at least with the "controlled" and "uncontrolled" terms.

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */
import {getCurrentFiberOwnerNameInDevOrNull} from 'react-reconciler/src/ReactCurrentFiber';
import invariant from 'shared/invariant';
import {setValueForProperty} from './DOMPropertyOperations';
import {getFiberCurrentPropsFromNode} from './ReactDOMComponentTree';
import {getToStringValue, toString} from './ToStringValue';
import {checkControlledValueProps} from '../shared/ReactControlledValuePropTypes';
import {updateValueIfChanged} from './inputValueTracking';
import {disableInputAttributeSyncing} from 'shared/ReactFeatureFlags';
import type {ToStringValue} from './ToStringValue';
type InputWithWrapperState = HTMLInputElement & {
  _wrapperState: {
    initialValue: ToStringValue,
    initialChecked: ?boolean,