Introduce "optimized_out" oddball marker for compilers.

src/compiler/js-graph.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/code-stubs.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/typer.h"
 
 namespace v8 {
@@ skipping 11 matching lines @@
   }
   return HeapConstant(CEntryStub(isolate(), result_size).GetCode());
 }
 
 
 Node* JSGraph::EmptyFixedArrayConstant() {
   return CACHED(kEmptyFixedArrayConstant,
                 HeapConstant(factory()->empty_fixed_array()));
 }
 
+Node* JSGraph::OptimizedOutConstant() {
+  return CACHED(kOptimizedOutConstant,
+                HeapConstant(factory()->optimized_out()));
+}
 
 Node* JSGraph::UndefinedConstant() {
   return CACHED(kUndefinedConstant, HeapConstant(factory()->undefined_value()));
 }
 
 
 Node* JSGraph::TheHoleConstant() {
   return CACHED(kTheHoleConstant, HeapConstant(factory()->the_hole_value()));
 }
 
@@ skipping 160 matching lines @@
   for (size_t i = 0; i < arraysize(cached_nodes_); i++) {
     if (Node* node = cached_nodes_[i]) {
       if (!node->IsDead()) nodes->push_back(node);
     }
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8