function isDefaultPropsDeclaration(node) {
      const propName = getPropertyName(node);
      return (propName === 'defaultProps' || propName === 'getDefaultProps');
    }
Checks if the Identifier node passed in looks like a defaultProps declaration.
@param   {ASTNode}  node The node to check. Must be an Identifier node.
@returns {boolean}       `true` if the node is a defaultProps declaration, `false` if not