[turbofan] Make sure value numbering only narrows types.

test/unittests/compiler/value-numbering-reducer-unittest.cc

Index: test/unittests/compiler/value-numbering-reducer-unittest.cc
diff --git a/test/unittests/compiler/value-numbering-reducer-unittest.cc b/test/unittests/compiler/value-numbering-reducer-unittest.cc
index c003033940024d8ec500e4b9b9fac2e464d979f5..c04d6609a77d187b77a27d2e07a4c75b40b13f48 100644
--- a/test/unittests/compiler/value-numbering-reducer-unittest.cc
+++ b/test/unittests/compiler/value-numbering-reducer-unittest.cc
@@ -28,7 +28,8 @@ static const TestOperator kOp1(1, Operator::kIdempotent, 1, 1);
 
 class ValueNumberingReducerTest : public TestWithZone {
  public:
-  ValueNumberingReducerTest() : graph_(zone()), reducer_(zone()) {}
+  ValueNumberingReducerTest()
+      : graph_(zone()), reducer_(zone(), graph()->zone()) {}
 
  protected:
   Reduction Reduce(Node* node) { return reducer_.Reduce(node); }