Bug 1759514 - Disable stacking context display item reuse in Nightly r=mstange

Differential Revision: https://phabricator.services.mozilla.com/D140980

modules/libpref/init/StaticPrefList.yaml

@@ -7927,7 +7927,7 @@
 
 - name: layout.display-list.retain.sc
   type: RelaxedAtomicBool
-  value: @IS_NIGHTLY_BUILD@
+  value: false
   mirror: always
 
 # Set the maximum number of modified frames allowed before doing a full