Revert 289489 "Ensure there's no layout pending before accessing..."

Revert 289489 "Ensure there's no layout pending before accessing..."

accessibility/deleting-iframe-destroys-axcache.html started to fail after this CL.
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/20592

> Ensure there's no layout pending before accessing WebAXObject from TestRunner.
> 
> It's not safe to call WebAXObject functions when there's a layout pending.
> Chrome never does this, it only calls WebAXObject from
> renderer_accessibility_complete, and it makes sure to update layout before
> accessing the accessibility tree.
> 
> TestRunner didn't have the same protections, so this just explicitly updates
> the layout before any accessibility call.
> 
> BUG=393829
> 
> Review URL: https://codereview.chromium.org/469803003

TBR=dmazzoni@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289515

[haraken, 2014-08-14 10:54:24]

Committed patchset #1 manually as r289515 (tree was closed).