function isPropTypesDeclaration(node) {
  if (node && (node.type === 'ClassProperty' || node.type === 'PropertyDefinition')) {
    // Flow support
    if (node.typeAnnotation && node.key.name === 'props') {
      return true;
    }
  }
  return astUtil.getPropertyName(node) === 'propTypes';
}
Checks if the Identifier node passed in looks like a propTypes declaration.
@param {ASTNode} node The node to check. Must be an Identifier node.
@returns {boolean} `true` if the node is a propTypes declaration, `false` if not