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

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

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/common-operator-reducer.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/machine-type.h"
 #include "src/compiler/operator.h"
 #include "src/compiler/simplified-operator.h"
@@ skipping 169 matching lines @@
         common()->Branch(hint),
         graph()->NewNode(simplified()->BooleanNot(), value), control);
     Node* const if_true = graph()->NewNode(common()->IfTrue(), branch);
     Node* const if_false = graph()->NewNode(common()->IfFalse(), branch);
     Reduction const r = Reduce(branch);
     ASSERT_TRUE(r.Changed());
     EXPECT_EQ(branch, r.replacement());
     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()));
   }
 }
 
 
 // -----------------------------------------------------------------------------
 // Merge
 
 
 TEST_F(CommonOperatorReducerTest, MergeOfUnusedDiamond0) {
   Node* const value = Parameter(0);
@@ skipping 405 matching lines @@
   Node* select =
       graph()->NewNode(common()->Select(kMachFloat64), check, p0, p1);
   Reduction r = Reduce(select, MachineOperatorBuilder::kFloat64Min);
   ASSERT_TRUE(r.Changed());
   EXPECT_THAT(r.replacement(), IsFloat64Min(p0, p1));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8