[Interpreter] Add ForInPrepare runtime function which returns a ObjectTriple.

src/mips/macro-assembler-mips.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_MIPS_MACRO_ASSEMBLER_MIPS_H_
 #define V8_MIPS_MACRO_ASSEMBLER_MIPS_H_
 
 #include "src/assembler.h"
 #include "src/globals.h"
 #include "src/mips/assembler-mips.h"
 
 namespace v8 {
 namespace internal {
 
 // Give alias names to registers for calling conventions.
 const Register kReturnRegister0 = {Register::kCode_v0};
 const Register kReturnRegister1 = {Register::kCode_v1};
+const Register kReturnRegister2 = {Register::kCode_a0};
 const Register kJSFunctionRegister = {Register::kCode_a1};
 const Register kContextRegister = {Register::kCpRegister};
 const Register kInterpreterAccumulatorRegister = {Register::kCode_v0};
 const Register kInterpreterRegisterFileRegister = {Register::kCode_t3};
 const Register kInterpreterBytecodeOffsetRegister = {Register::kCode_t4};
 const Register kInterpreterBytecodeArrayRegister = {Register::kCode_t5};
 const Register kInterpreterDispatchTableRegister = {Register::kCode_t6};
 const Register kJavaScriptCallArgCountRegister = {Register::kCode_a0};
 const Register kJavaScriptCallNewTargetRegister = {Register::kCode_a3};
 const Register kRuntimeCallFunctionRegister = {Register::kCode_a1};
@@ skipping 1729 matching lines @@
 #define __FILE_LINE__ __FILE__ ":" CODE_COVERAGE_TOSTRING(__LINE__)
 #define ACCESS_MASM(masm) masm->stop(__FILE_LINE__); masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_MIPS_MACRO_ASSEMBLER_MIPS_H_