function isValidComponentDescriptor(descriptor) {
  return (
    descriptor &&
    typeof descriptor.type === 'function' &&
    typeof descriptor.type.prototype.mountComponent === 'function' &&
    typeof descriptor.type.prototype.receiveComponent === 'function'
  );
}
Validate a `componentDescriptor`. This should be exposed publicly in a follow
up diff.

@param {object} descriptor
@return {boolean} Returns true if this is a valid descriptor of a Component.