[orca-list] Bisected a performance regression in Browse mode when using Chromium

[am_dxer fastmail fm]

Hi there,
I noticed a regression in browse mode. As a bit of background, I disable layout mode for browsing on the 
Chromium tab for more speed when down arrowing. The following commit causes a regression that can be noticed 
obviously if you hold the down arrow even on faster machines. Is there anything that can be done to lessen 
the impact of this. Its particularly noticeable on netbook type machines with fanless chips, even modern ones 
like celeron n4000 etc and moves the Orca Chromium team from very quick to frustratingly slow. Thanks in 
advance for looking into this.

# first bad commit: [3d165897debb26aab2ef930a142da74b54872d98] Chromium: Don't cache the accessible parent