Print promotion rate and semi-space copy rate in --trace-gc-nvp.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index d0d35473912f9588981f1924c5df16eedbe40268..074754c8665127668d711eea949db2d61bf2990e 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -2604,6 +2604,10 @@ class GCTracer BASE_EMBEDDED {
     promoted_objects_size_ += object_size;
   }
 
+  void increment_semi_space_copied_object_size(int object_size) {
+    semi_space_copied_object_size_ += object_size;
+  }
+
   void increment_nodes_died_in_new_space() {
     nodes_died_in_new_space_++;
   }
@@ -2660,6 +2664,10 @@ class GCTracer BASE_EMBEDDED {
   // Size of objects promoted during the current collection.
   intptr_t promoted_objects_size_;
 
+  // Size of objects copied to the other semi-space during the current
+  // collection.
+  intptr_t semi_space_copied_object_size_;
+
   // Number of died nodes in the new space.
   int nodes_died_in_new_space_;