[turbofan] Optimize tagged conversion based on type.

src/compiler/change-lowering.h

Index: src/compiler/change-lowering.h
diff --git a/src/compiler/change-lowering.h b/src/compiler/change-lowering.h
index 2997d2554bcce38ba759d8b79e98d802863a8038..a41119016508ac03a907c62761d83136e037b207 100644
--- a/src/compiler/change-lowering.h
+++ b/src/compiler/change-lowering.h
@@ -44,6 +44,7 @@ class ChangeLowering final : public Reducer {
   Reduction ChangeBitToBool(Node* value, Node* control);
   Reduction ChangeBoolToBit(Node* value);
   Reduction ChangeFloat64ToTagged(Node* value, Node* control);
+  Reduction ChangeInt31ToTagged(Node* value, Node* control);
   Reduction ChangeInt32ToTagged(Node* value, Node* control);
   Reduction ChangeSmiToInt32(Node* value);
   Reduction ChangeTaggedToFloat64(Node* value, Node* control);