[turbofan] Use the typer to statically detect Smis.

test/unittests/compiler/change-lowering-unittest.cc

Index: test/unittests/compiler/change-lowering-unittest.cc
diff --git a/test/unittests/compiler/change-lowering-unittest.cc b/test/unittests/compiler/change-lowering-unittest.cc
index 5b31f5e04cc90bd6e6af0de5d9969c565977da94..50119ece2d54efef51f92aff4294302891f30f7d 100644
--- a/test/unittests/compiler/change-lowering-unittest.cc
+++ b/test/unittests/compiler/change-lowering-unittest.cc
@@ -181,7 +181,7 @@ class ChangeLowering32Test : public ChangeLoweringTest {
 TARGET_TEST_F(ChangeLowering32Test, ChangeInt32ToTagged) {
   Node* val = Parameter(0);
   Node* node = graph()->NewNode(simplified()->ChangeInt32ToTagged(), val);
-  NodeProperties::SetBounds(val, Bounds(Type::None(), Type::Signed32()));
+  NodeProperties::SetBounds(val, Bounds(Type::None(), Type::Integral32()));
   Reduction reduction = Reduce(node);
   ASSERT_TRUE(reduction.Changed());
 
@@ -209,7 +209,7 @@ TARGET_TEST_F(ChangeLowering32Test, ChangeInt32ToTagged) {
 TARGET_TEST_F(ChangeLowering32Test, ChangeInt32ToTaggedSmall) {
   Node* val = Parameter(0);
   Node* node = graph()->NewNode(simplified()->ChangeInt32ToTagged(), val);
-  NodeProperties::SetBounds(val, Bounds(Type::None(), Type::Signed31()));
+  NodeProperties::SetBounds(val, Bounds(Type::None(), Type::SignedSmall()));
   Reduction reduction = Reduce(node);
   ASSERT_TRUE(reduction.Changed());