Clarify side effects of HTransitionElementsKind.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index a4c54e761e731944247005f0b940df7804617206..28101d8fa507d6fd2ab55024dbf737f899dd3cad 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -3085,6 +3085,7 @@ void HTransitionElementsKind::PrintDataTo(StringStream* stream) {
               ElementsAccessor::ForKind(from_kind)->name(),
               *transitioned_map(),
               ElementsAccessor::ForKind(to_kind)->name());
+  if (IsSimpleMapChangeTransition(from_kind, to_kind)) stream->Add(" (simple)");
 }