[turbofan] Fix tail call optimization.

src/compiler/tail-call-optimization.h

Index: src/compiler/tail-call-optimization.h
diff --git a/src/compiler/tail-call-optimization.h b/src/compiler/tail-call-optimization.h
new file mode 100644
index 0000000000000000000000000000000000000000..b5d4f961fe52ebe5ee4f2f30b7b9e6780374c07f
--- /dev/null
+++ b/src/compiler/tail-call-optimization.h
@@ -0,0 +1,40 @@
+// Copyright 2015 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.
+
+#ifndef V8_COMPILER_TAIL_CALL_OPTIMIZATION_H_
+#define V8_COMPILER_TAIL_CALL_OPTIMIZATION_H_
+
+#include "src/compiler/graph-reducer.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+// Forward declarations.
+class CommonOperatorBuilder;
+class Graph;
+
+
+// Performs tail call optimization by replacing certain combinations of Return
+// and Call nodes with a single TailCall.
+class TailCallOptimization final : public Reducer {
+ public:
+  TailCallOptimization(CommonOperatorBuilder* common, Graph* graph)
+      : common_(common), graph_(graph) {}
+
+  Reduction Reduce(Node* node) final;
+
+ private:
+  CommonOperatorBuilder* common() const { return common_; }
+  Graph* graph() const { return graph_; }
+
+  CommonOperatorBuilder* const common_;
+  Graph* const graph_;
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_TAIL_CALL_OPTIMIZATION_H_