[es6] Tail calls support.

src/code-stubs.h

 // Copyright 2012 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_CODE_STUBS_H_
 #define V8_CODE_STUBS_H_
 
 #include "src/allocation.h"
 #include "src/assembler.h"
 #include "src/codegen.h"
@@ skipping 907 matching lines @@
 
   InlineCacheState GetICState() const override { return GENERIC; }
 
   ExtraICState GetExtraICState() const final {
     return static_cast<ExtraICState>(minor_key_);
   }
 
  protected:
   int arg_count() const { return state().argc(); }
   ConvertReceiverMode convert_mode() const { return state().convert_mode(); }
+  TailCallMode tail_call_mode() const { return state().tail_call_mode(); }
 
   CallICState state() const {
     return CallICState(static_cast<ExtraICState>(minor_key_));
   }
 
   // Code generation helpers.
   void GenerateMiss(MacroAssembler* masm);
   void HandleArrayCase(MacroAssembler* masm, Label* miss);
 
  private:
@@ skipping 2046 matching lines @@
 #undef DEFINE_HYDROGEN_CODE_STUB
 #undef DEFINE_CODE_STUB
 #undef DEFINE_CODE_STUB_BASE
 
 extern Representation RepresentationFromType(Type* type);
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CODE_STUBS_H_