[turbofan] Introduce CheckTaggedSigned and CheckTaggedPointer operators.

test/unittests/compiler/instruction-selector-unittest.cc

Index: test/unittests/compiler/instruction-selector-unittest.cc
diff --git a/test/unittests/compiler/instruction-selector-unittest.cc b/test/unittests/compiler/instruction-selector-unittest.cc
index 9b1b40e51b51ea0c6118fc1ee9dfa2ef2d66dc7a..a0a78916602306b28d9d869157e7fbf21466ce2b 100644
--- a/test/unittests/compiler/instruction-selector-unittest.cc
+++ b/test/unittests/compiler/instruction-selector-unittest.cc
@@ -333,7 +333,8 @@ TARGET_TEST_F(InstructionSelectorTest, ValueEffect) {
   Node* p2 = m2.Parameter(0);
   m2.Return(m2.AddNode(
       m2.machine()->Load(MachineType::Int32()), p2, m2.Int32Constant(0),
-      m2.AddNode(m2.common()->BeginRegion(), m2.graph()->start())));
+      m2.AddNode(m2.common()->BeginRegion(RegionObservability::kObservable),
+                 m2.graph()->start())));
   Stream s2 = m2.Build(kAllInstructions);
   EXPECT_LE(3U, s1.size());
   ASSERT_EQ(s1.size(), s2.size());