Flash: Remove all params that match the defaults

As a follow up to &3895 (closed), we should update this spec.

The following discussion from !63645 (merged) should be addressed:

• @justin_ho started a discussion:

  Nit: Can we create a follow-up to remove all params that match the defaults? For example, actionConfig is already null by default and so is parent: document.

The defaults are:

type = FLASH_TYPES.ALERT
parent = document
actionConfig = null
fadeTransition = true
addBodyClass = false
captureError = false
error = null