[turbofan] Introduce CheckIf node (deopt without explicit frame state).

src/compiler/simplified-operator.cc

Index: src/compiler/simplified-operator.cc
diff --git a/src/compiler/simplified-operator.cc b/src/compiler/simplified-operator.cc
index aa5b397104727ad0bac3031f2f216e881261c261..e906acbf880043060b3e6a94f3271506f82bf462 100644
--- a/src/compiler/simplified-operator.cc
+++ b/src/compiler/simplified-operator.cc
@@ -261,6 +261,13 @@ struct SimplifiedOperatorGlobalCache final {
   CHECKED_OP_LIST(CHECKED)
 #undef CHECKED
 
+  struct CheckIfOperator final : public Operator {
+    CheckIfOperator()
+        : Operator(IrOpcode::kCheckIf, Operator::kFoldable, "CheckIf", 1, 1, 1,
+                   0, 1, 1) {}
+  };
+  CheckIfOperator kCheckIf;
+
   template <PretenureFlag kPretenure>
   struct AllocateOperator final : public Operator1<PretenureFlag> {
     AllocateOperator()
@@ -309,6 +316,10 @@ PURE_OP_LIST(GET_FROM_CACHE)
 CHECKED_OP_LIST(GET_FROM_CACHE)
 #undef GET_FROM_CACHE
 
+const Operator* SimplifiedOperatorBuilder::CheckIf() {
+  return &cache_.kCheckIf;
+}
+
 const Operator* SimplifiedOperatorBuilder::ReferenceEqual(Type* type) {
   return new (zone()) Operator(IrOpcode::kReferenceEqual,
                                Operator::kCommutative | Operator::kPure,