function getHostProps(element, props) {
    var node = element;
    var checked = props.checked;
    var hostProps = assign({}, props, {
      defaultChecked: undefined,
      defaultValue: undefined,
      value: undefined,
      checked: checked != null ? checked : node._wrapperState.initialChecked
    });
    return hostProps;
  }
Implements an <input> host component that allows setting these optional
props: `checked`, `value`, `defaultChecked`, and `defaultValue`.

If `checked` or `value` are not supplied (or null/undefined), user actions
that affect the checked state or value will trigger updates to the element.

If they are supplied (and not null/undefined), the rendered element will not
trigger updates to the element. Instead, the props must change in order for
the rendered element to be updated.

The rendered element will be initialized as unchecked (or `defaultChecked`)
with an empty value (or `defaultValue`).

See http://www.w3.org/TR/2012/WD-html5-20121025/the-input-element.html