Differ: remove incorrect comment

Summary:
This is no longer true because of the "scope" mechanism.

Changelog: [Internal]

Reviewed By: sammy-SC

Differential Revision: D28018995

fbshipit-source-id: 91470234bb15f7feeb92b41613b0bbdbe42ccb27

ReactCommon/react/renderer/mounting/Differentiator.cpp

@@ -937,8 +937,6 @@ static void calculateShadowViewMutationsFlattener(
           else {
             // Construct unvisited nodes map
             auto unvisitedOldChildPairs = TinyMap<Tag, ShadowViewNodePair *>{};
-            // Memory note: these oldFlattenedNodes all disappear at the end
-            // of this "else" block, including any annotations we put on them.
             auto oldFlattenedNodes =
                 sliceChildShadowNodeViewPairsFromViewNodePair(
                     oldTreeNodePair, scope, true);