disappearing menu on plugin admin route due to r32089

[nerrad]

Noticed this today after updating WP to 4.2-beta4-32091 on one of our plugin routes:

Traced it to [32089] for #30900

If I revert the css in that change, the menus are back. We're checking to see if this happens with what we have posted on wp.org and if it does I'll linky here. We're also seeing if we can reproduce with any other plugin menus.

I'm not ruling out that this is a conflict with some css on our plugin but wanted to just get this up in case it definitely is a core issue.

[nerrad]

you can reproduce using the current version of our wp.org plugin -> ​https://wordpress.org/plugins/event-espresso-decaf/

[nerrad]

K found it, our plugin has some css that was conflicting

`
#adminmenuwrap { z-index : 1001; }
`

removed that and all is good.