[turbofan] Also update the BranchHint when merging a BooleanNot.

test/unittests/compiler/common-operator-reducer-unittest.cc

Index: test/unittests/compiler/common-operator-reducer-unittest.cc
diff --git a/test/unittests/compiler/common-operator-reducer-unittest.cc b/test/unittests/compiler/common-operator-reducer-unittest.cc
index c33d10700b923f0420ce8556d9f9d890a6350825..13d2d6707a23bfc78ee5a9247791a70156e3716c 100644
--- a/test/unittests/compiler/common-operator-reducer-unittest.cc
+++ b/test/unittests/compiler/common-operator-reducer-unittest.cc
@@ -187,6 +187,7 @@ TEST_F(CommonOperatorReducerTest, BranchWithBooleanNot) {
     EXPECT_THAT(branch, IsBranch(value, control));
     EXPECT_THAT(if_false, IsIfTrue(branch));
     EXPECT_THAT(if_true, IsIfFalse(branch));
+    EXPECT_EQ(NegateBranchHint(hint), BranchHintOf(branch->op()));
   }
 }