code: function checkAndWarnForMutatedProps(element) {
    if (!element._store) {
      // Element was created using `new ReactElement` directly or with
      // `ReactElement.createElement`; skip mutation checking
      return;
    }
  
    var originalProps = element._store.originalProps;
    var props = element.props;
  
    for (var propName in props) {
      if (props.hasOwnProperty(propName)) {
        if (!originalProps.hasOwnProperty(propName) ||
            !is(originalProps[propName], props[propName])) {
          warnForPropsMutation(propName, element);
  
          // Copy over the new value so that the two props objects match again
          originalProps[propName] = props[propName];
        }
      }
    }
  }
docs: Given an element, check if its props have been mutated since element
  creation (or the last call to this function). In particular, check if any
  new props have been added, which we can't directly catch by defining warning
  properties on the props object.
  
  @param {ReactElement} element