Revert of Don't keep recreating AXMenuListPopup

Revert of Don't keep recreating AXMenuListPopup (patchset #8 id:140001 of https://codereview.chromium.org/1059503002/)

Reason for revert:
This appears to be blocking the Blink roll due to the failure of DumpAccessibilityTreeTest.AccessibilityModalDialogClosed

See, for example, this attempted roll: https://codereview.chromium.org/1068753002/

Original issue's description:
> Don't keep recreating AXMenuListPopup
> 
> Every time an AXMenuList (corresponding to a
> <select> element) needed to update its children,
> we were recreating the AXMenuListPopup and
> all of the AXMenuListOptions each time, which is
> wasteful. This change avoids deleting the popup
> and stores the options in AXObjectCache by
> element, rather than by ID, so they can be reused
> when the options are updated.
> 
> BUG=323462
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=193251

TBR=je_julie.kim@samsung.com,dmazzoni@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=323462
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=193286

[Stephen Chennney, 2015-04-07 17:54:50]

Created Revert of Don't keep recreating AXMenuListPopup

[commit-bot: I haz the power, 2015-04-07 17:55:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1061063004/1

[commit-bot: I haz the power, 2015-04-07 17:56:42]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=193286