[turbofan] Introduce DeadValue and DeadEffect operators.

src/compiler/typer.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/base/flags.h"
 #include "src/bootstrapper.h"
 #include "src/compiler/graph-reducer.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/node.h"
 #include "src/compiler/node-properties.h"
@@ skipping 724 matching lines @@
   UNREACHABLE();
   return Bounds();
 }
 
 
 Bounds Typer::Visitor::TypeFinish(Node* node) {
   return Operand(node, 0);
 }
 
 
+Bounds Typer::Visitor::TypeDeadValue(Node* node) {
+  return Bounds(Type::None(zone()), Type::Any(zone()));
+}
+
+
+Bounds Typer::Visitor::TypeDeadEffect(Node* node) {
+  UNREACHABLE();
+  return Bounds();
+}
+
+
 Bounds Typer::Visitor::TypeFrameState(Node* node) {
   // TODO(rossberg): Ideally FrameState wouldn't have a value output.
   return Bounds(Type::None(zone()), Type::Internal(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeStateValues(Node* node) {
   return Bounds(Type::None(zone()), Type::Internal(zone()));
 }
 
@@ skipping 1663 matching lines @@
       TYPED_ARRAYS(TYPED_ARRAY_CASE)
 #undef TYPED_ARRAY_CASE
     }
   }
   return Type::Constant(value, zone());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8