Introduce flag --allocation-site-transitioning

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 59efdf0a89269799f4b9bd5ddc8ef766f04b77e6..2de533a3eb22187a02453fe1fb3dfdb5b8705da9 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -1604,7 +1604,8 @@ void AllocationSite::MarkZombie() {
 AllocationSiteMode AllocationSite::GetMode(
     ElementsKind boilerplate_elements_kind) {
   if (FLAG_pretenuring_call_new ||
-      IsFastSmiElementsKind(boilerplate_elements_kind)) {
+      (FLAG_allocation_site_transitioning &&
+       IsFastSmiElementsKind(boilerplate_elements_kind))) {
     return TRACK_ALLOCATION_SITE;
   }
 
@@ -1615,7 +1616,7 @@ AllocationSiteMode AllocationSite::GetMode(
 AllocationSiteMode AllocationSite::GetMode(ElementsKind from,
                                            ElementsKind to) {
   if (FLAG_pretenuring_call_new ||
-      (IsFastSmiElementsKind(from) &&
+      (FLAG_allocation_site_transitioning && IsFastSmiElementsKind(from) &&
        IsMoreGeneralElementsKindTransition(from, to))) {
     return TRACK_ALLOCATION_SITE;
   }
@@ -1630,7 +1631,7 @@ inline bool AllocationSite::CanTrack(InstanceType type) {
         type == JS_OBJECT_TYPE ||
         type < FIRST_NONSTRING_TYPE;
   }
-  return type == JS_ARRAY_TYPE;
+  return FLAG_allocation_site_transitioning && type == JS_ARRAY_TYPE;
 }