[interpreter] Add Interpreter{Entry,Exit}Trampoline builtins.

src/interpreter/interpreter.cc

 // 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.
 
 #include "src/interpreter/interpreter.h"
 
 #include "src/compiler.h"
 #include "src/compiler/interpreter-assembler.h"
 #include "src/factory.h"
 #include "src/interpreter/bytecodes.h"
@@ skipping 41 matching lines @@
 // argument.
 void Interpreter::DoLoadLiteral0(compiler::InterpreterAssembler* assembler) {
   Node* register_index = __ BytecodeArg(0);
   __ StoreRegister(__ NumberConstant(0), register_index);
   __ Dispatch();
 }
 
 
 // Return the value in register 0.
 void Interpreter::DoReturn(compiler::InterpreterAssembler* assembler) {
-  // TODO(rmcilroy) Jump to exit trampoline.
+  __ Return();
 }
 
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8