Add scavenger events to GC tracer

src/heap/gc-tracer.h

Index: src/heap/gc-tracer.h
diff --git a/src/heap/gc-tracer.h b/src/heap/gc-tracer.h
index 468fc9c0be7c4c298e2eb6a03580ff6be66f6505..64f43bc4d0f4eb8408f418efacdc02bfa1b867bb 100644
--- a/src/heap/gc-tracer.h
+++ b/src/heap/gc-tracer.h
@@ -117,6 +117,13 @@ class GCTracer {
       MC_WEAKCOLLECTION_CLEAR,
       MC_WEAKCOLLECTION_ABORT,
       MC_FLUSH_CODE,
+      SCAVENGER_CODE_FLUSH_CANDIDATES,
+      SCAVENGER_OBJECT_GROUPS,
+      SCAVENGER_OLD_TO_NEW_POINTERS,
+      SCAVENGER_ROOTS,
+      SCAVENGER_SCAVENGE,
+      SCAVENGER_SEMISPACE,
+      SCAVENGER_WEAK,
       NUMBER_OF_SCOPES
     };