freed_nodes in global-handles should be addititive

src/global-handles.cc

Index: src/global-handles.cc
diff --git a/src/global-handles.cc b/src/global-handles.cc
index d8073aa65043cf6222fb0431ff1e1ea37a2b36df..6a6b6ef8603b23e47654f9bc531191d2cb649f82 100644
--- a/src/global-handles.cc
+++ b/src/global-handles.cc
@@ -849,9 +849,9 @@ int GlobalHandles::PostGarbageCollectionProcessing(GarbageCollector collector) {
     return freed_nodes;
   }
   if (collector == SCAVENGER) {
-    freed_nodes = PostScavengeProcessing(initial_post_gc_processing_count);
+    freed_nodes += PostScavengeProcessing(initial_post_gc_processing_count);
   } else {
-    freed_nodes = PostMarkSweepProcessing(initial_post_gc_processing_count);
+    freed_nodes += PostMarkSweepProcessing(initial_post_gc_processing_count);
   }
   if (initial_post_gc_processing_count != post_gc_processing_count_) {
     // If the callbacks caused a nested GC, then return.  See comment in