Implement TreeSortedMap::insert (#1081)

* Make LlrbNode Rep more explicit, share empty node

* SortedMap::insert converts implementations

* Implement LlrbNode::insert

* Remove TestPolicy<SortedMap>

1 files changed, 4 insertions, 0 deletions

diff --git a/Firestore/core/src/firebase/firestore/immutable/map_entry.h b/Firestore/core/src/firebase/firestore/immutable/map_entry.h
index 1022b06..b2b3c97 100644
--- a/Firestore/core/src/firebase/firestore/immutable/map_entry.h
+++ b/Firestore/core/src/firebase/firestore/immutable/map_entry.h
@@ -51,6 +51,10 @@ struct KeyComparator {
     return key_comparator_(lhs.first, rhs.first);
   }
 
+  const C& comparator() const {
+    return key_comparator_;
+  }
+
  private:
   C key_comparator_;
 };