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

src/compiler/common-operator-reducer.cc

Index: src/compiler/common-operator-reducer.cc
diff --git a/src/compiler/common-operator-reducer.cc b/src/compiler/common-operator-reducer.cc
index 1ed05f1834bf7b214db79526d8fc5a2f3698c736..c1cd75ef7beb26698ea8ae61b1adbe2531de7041 100644
--- a/src/compiler/common-operator-reducer.cc
+++ b/src/compiler/common-operator-reducer.cc
@@ -99,6 +99,8 @@ Reduction CommonOperatorReducer::ReduceBranch(Node* node) {
     // since we tell the graph reducer that the {branch} was changed and the
     // graph reduction logic will ensure that the uses are revisited properly.
     node->ReplaceInput(0, cond->InputAt(0));
+    // Negate the hint for {branch}.
+    node->set_op(common()->Branch(NegateBranchHint(BranchHintOf(node->op()))));
     return Changed(node);
   }
   Decision const decision = DecideCondition(cond);