[turbofan] Minor cleanup to reduce code duplication.

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 e7abe23ece6825e9706fe5c067c0b07ff935ac09..199fb30cc6bd1b65f434ecf07c6d4fb1f2de8db9 100644
--- a/test/unittests/compiler/change-lowering-unittest.cc
+++ b/test/unittests/compiler/change-lowering-unittest.cc
@@ -61,10 +61,6 @@ class ChangeLoweringTest : public GraphTest {
                   : SmiTagging<8>::SmiValueSize();
   }
 
-  Node* Parameter(int32_t index = 0) {
-    return graph()->NewNode(common()->Parameter(index), graph()->start());
-  }
-
   Reduction Reduce(Node* node) {
     MachineOperatorBuilder machine(zone(), WordRepresentation());
     JSOperatorBuilder javascript(zone());