Backed out changeset 2bfb5438d2ae (bug 1805401) for causing python failures on lint.py

toolkit/moz.configure

@@ -2531,7 +2531,8 @@ wasm_sandboxing_config_defines()
 
 @depends(milestone)
 def new_xulstore(milestone):
-    return False
+    if milestone.is_nightly:
+        return True
 
 
 set_config("MOZ_NEW_XULSTORE", True, when=new_xulstore)