Accordion: fixes #9264

Using .show method and outerHeight property to force height calculation when
heightStyle='auto'
This addresses the "snap" issue referenced in the ticket and works for all valid values of heightStyle.  However, I haven't been able to generate an automated test case, since
`fx.now = Math.round( total - toHide.outerHeight() - adjust);` 
seems to be calculating correctly.  That would seem to indicate the problem is with the tween processing but I haven't been able to lock down precisely where - I can only confirm that omitting the tween processing solves the problem.