[turbofan] Smartify the GraphReducer.

test/unittests/compiler/graph-reducer-unittest.cc

Index: test/unittests/compiler/graph-reducer-unittest.cc
diff --git a/test/unittests/compiler/graph-reducer-unittest.cc b/test/unittests/compiler/graph-reducer-unittest.cc
index 88f25f7b1b2e76b237098bf7500e91e86c4770ab..7072960eba291d19f17e87b05523cd649202f805 100644
--- a/test/unittests/compiler/graph-reducer-unittest.cc
+++ b/test/unittests/compiler/graph-reducer-unittest.cc
@@ -87,6 +87,7 @@ TEST_F(GraphReducerTest, NodeIsDeadAfterReplace) {
   Node* node0 = graph()->NewNode(&OP0);
   Node* node1 = graph()->NewNode(&OP1, node0);
   Node* node2 = graph()->NewNode(&OP1, node0);
+  EXPECT_CALL(r, Reduce(node0)).WillOnce(Return(Reducer::NoChange()));
   EXPECT_CALL(r, Reduce(node1)).WillOnce(Return(Reducer::Replace(node2)));
   ReduceNode(node1, &r);
   EXPECT_FALSE(node0->IsDead());
@@ -114,7 +115,6 @@ TEST_F(GraphReducerTest, ReduceAgainAfterChanged) {
       Return(Reducer::Changed(node0)));
   EXPECT_CALL(r1, Reduce(node0)).InSequence(s1);
   EXPECT_CALL(r2, Reduce(node0)).InSequence(s2);
-  EXPECT_CALL(r3, Reduce(node0)).InSequence(s3);
   ReduceNode(node0, &r1, &r2, &r3);
 }