Bug 1640605 - Remove IsInAnonymousSubtree / IsRootOfAnonymousSubtree. r=edgar

In favor of the NativeAnonymous versions which they forward to.

Done automatically with:

  rg -l 'IsInAnonymousSubtree' | xargs sed -i 's/IsInAnonymousSubtree/IsInNativeAnonymousSubtree/g'

And removing the function definitions afterwards.

Differential Revision: https://phabricator.services.mozilla.com/D76681

layout/base/PresShell.cpp

@@ -4402,7 +4402,7 @@ MOZ_CAN_RUN_SCRIPT_BOUNDARY void PresShell::ContentRemoved(
 
   // Editor calls into here with NAC via HTMLEditor::DeleteRefToAnonymousNode.
   // This could be asserted if that caller is fixed.
-  if (MOZ_LIKELY(!aChild->IsRootOfAnonymousSubtree())) {
+  if (MOZ_LIKELY(!aChild->IsRootOfNativeAnonymousSubtree())) {
     oldNextSibling = aPreviousSibling ? aPreviousSibling->GetNextSibling()
                                       : container->GetFirstChild();
   }