CABackdropFilter should set windowServerAware to false
<rdar://problem/21618614>
Created attachment 255847 [details] Patch
Not sure if this is available on Yosemite. EWS will tell me!
Created attachment 255854 [details] Patch
Created attachment 255855 [details] Patch
Committed r186139: <http://trac.webkit.org/changeset/186139>