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

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 0f6f55a80176f179551630f898eff3a84c7e3ec4..0282da43ba1e164e1120e98c39bfa2e63f31d515 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -1945,6 +1945,11 @@ Type* Typer::Visitor::TypeCheckedTaggedToFloat64(Node* node) {
   return Type::Number();
 }
 
+Type* Typer::Visitor::TypeCheckIf(Node* node) {
+  UNREACHABLE();
+  return nullptr;
+}
+
 Type* Typer::Visitor::TypeTruncateTaggedToWord32(Node* node) {
   Type* arg = Operand(node, 0);
   // TODO(jarin): DCHECK(arg->Is(Type::NumberOrUndefined()));