[turbofan] Introduce dedicated ObjectIsNaN operator.

test/unittests/compiler/js-builtin-reducer-unittest.cc

Index: test/unittests/compiler/js-builtin-reducer-unittest.cc
diff --git a/test/unittests/compiler/js-builtin-reducer-unittest.cc b/test/unittests/compiler/js-builtin-reducer-unittest.cc
index a4332042cbc536eb040c8e94ba77a0b2d90c78c4..3237feaa4572aff2424e4c1cc0dc705cc147c924 100644
--- a/test/unittests/compiler/js-builtin-reducer-unittest.cc
+++ b/test/unittests/compiler/js-builtin-reducer-unittest.cc
@@ -1475,7 +1475,7 @@ TEST_F(JSBuiltinReducerTest, NumberIsNaNWithNumber) {
     Reduction r = Reduce(call);
 
     ASSERT_TRUE(r.Changed());
-    EXPECT_THAT(r.replacement(), IsBooleanNot(IsNumberEqual(p0, p0)));
+    EXPECT_THAT(r.replacement(), IsObjectIsNaN(p0));
   }
 }