[turbofan] Smartify the GraphReducer.

test/cctest/compiler/test-changes-lowering.cc

Index: test/cctest/compiler/test-changes-lowering.cc
diff --git a/test/cctest/compiler/test-changes-lowering.cc b/test/cctest/compiler/test-changes-lowering.cc
index 02ba4a7fb156b95203b88dde7129549715e9b181..34c8c5bb6c0fbc3289a56bdd7400589d4b013050 100644
--- a/test/cctest/compiler/test-changes-lowering.cc
+++ b/test/cctest/compiler/test-changes-lowering.cc
@@ -129,7 +129,7 @@ class ChangesLoweringTester : public GraphBuilderTester<ReturnType> {
     Linkage linkage(this->zone(), &info);
     ChangeLowering change_lowering(&jsgraph, &linkage);
     SelectLowering select_lowering(this->graph(), this->common());
-    GraphReducer reducer(this->graph());
+    GraphReducer reducer(this->graph(), this->zone());
     reducer.AddReducer(&change_lowering);
     reducer.AddReducer(&select_lowering);
     reducer.ReduceNode(change);