Kill off assert macro (cherry picked from commit d6493abedb2caf03b2bc3a6440b637df67eff081)
(cherry picked from commit 08ebf86d379b1ddfb08df65d29aea5df66de4327)
Leaving xpr unflattened since we want modularity to replace that with xpc (XPluginComposite) at some point (cherry picked from commit 48e6a75fbdd0fee86e364f02ace83f20b312a2b2)