[Sync] Do not check IS_DIR bit on nigori node

sync/internal_api/base_node.cc

Index: sync/internal_api/base_node.cc
diff --git a/sync/internal_api/base_node.cc b/sync/internal_api/base_node.cc
index 29d4574fffce394072b2bb7032313ad3324994b3..d7c6380aaf11cd3bf73301b563948a90a11b809c 100644
--- a/sync/internal_api/base_node.cc
+++ b/sync/internal_api/base_node.cc
@@ -163,8 +163,9 @@ bool BaseNode::GetIsFolder() const {
 bool BaseNode::GetIsPermanentFolder() const {
   bool is_permanent_folder = !GetEntry()->GetUniqueServerTag().empty();
   if (is_permanent_folder) {
-    // If the node is a permanent folder it must also have IS_DIR bit set.
-    DCHECK(GetIsFolder());
+    // If the node is a permanent folder it must also have IS_DIR bit set,
+    // except some nigori nodes on old accounts.
+    DCHECK(GetIsFolder() || GetModelType() == NIGORI);
   }
   return is_permanent_folder;
 }