[es6] Introduce a dedicated JSIteratorResult type.

src/x64/macro-assembler-x64.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_X64_MACRO_ASSEMBLER_X64_H_
 #define V8_X64_MACRO_ASSEMBLER_X64_H_
 
 #include "src/assembler.h"
 #include "src/bailout-reason.h"
 #include "src/base/flags.h"
@@ skipping 115 matching lines @@
   // register.
   void LoadAddress(Register destination, ExternalReference source);
   // Returns the size of the code generated by LoadAddress.
   // Used by CallSize(ExternalReference) to find the size of a call.
   int LoadAddressSize(ExternalReference source);
   // Pushes the address of the external reference onto the stack.
   void PushAddress(ExternalReference source);
 
   // Operations on roots in the root-array.
   void LoadRoot(Register destination, Heap::RootListIndex index);
+  void LoadRoot(const Operand& destination, Heap::RootListIndex index) {
+    LoadRoot(kScratchRegister, index);
+    movp(destination, kScratchRegister);
+  }
   void StoreRoot(Register source, Heap::RootListIndex index);
   // Load a root value where the index (or part of it) is variable.
   // The variable_offset register is added to the fixed_offset value
   // to get the index into the root-array.
   void LoadRootIndexed(Register destination,
                        Register variable_offset,
                        int fixed_offset);
   void CompareRoot(Register with, Heap::RootListIndex index);
   void CompareRoot(const Operand& with, Heap::RootListIndex index);
   void PushRoot(Heap::RootListIndex index);
@@ skipping 1473 matching lines @@
     masm->popfq();                                                           \
   }                                                                          \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_