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

src/compiler/linkage.cc

 // Copyright 2014 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/ast/scopes.h"
 #include "src/code-stubs.h"
 #include "src/compiler.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/frame.h"
 #include "src/compiler/linkage.h"
@@ skipping 224 matching lines @@
   LocationSignature::Builder locations(zone, return_count, parameter_count);
   MachineSignature::Builder types(zone, return_count, parameter_count);
 
   // Add returns.
   if (locations.return_count_ > 0) {
     locations.AddReturn(regloc(kReturnRegister0));
   }
   if (locations.return_count_ > 1) {
     locations.AddReturn(regloc(kReturnRegister1));
   }
+  if (locations.return_count_ > 2) {
+    locations.AddReturn(regloc(kReturnRegister2));
+  }
   for (size_t i = 0; i < return_count; i++) {
     types.AddReturn(MachineType::AnyTagged());
   }
 
   // All parameters to the runtime call go on the stack.
   for (int i = 0; i < js_parameter_count; i++) {
     locations.AddParam(
         LinkageLocation::ForCallerFrameSlot(i - js_parameter_count));
     types.AddParam(MachineType::AnyTagged());
   }
@@ skipping 186 matching lines @@
   LocationSignature::Builder locations(zone, return_count, parameter_count);
   MachineSignature::Builder types(zone, return_count, parameter_count);
 
   // Add returns.
   if (locations.return_count_ > 0) {
     locations.AddReturn(regloc(kReturnRegister0));
   }
   if (locations.return_count_ > 1) {
     locations.AddReturn(regloc(kReturnRegister1));
   }
+  if (locations.return_count_ > 2) {
+    locations.AddReturn(regloc(kReturnRegister2));
+  }
   for (size_t i = 0; i < return_count; i++) {
     types.AddReturn(return_type);
   }
 
   // Add parameters in registers and on the stack.
   for (int i = 0; i < js_parameter_count; i++) {
     if (i < register_parameter_count) {
       // The first parameters go in registers.
       Register reg = descriptor.GetRegisterParameter(i);
       Representation rep =
@@ skipping 69 matching lines @@
   } else {
     DCHECK(loc == regloc(kContextRegister));
     return LinkageLocation::ForCalleeFrameSlot(Frame::kContextSlot);
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8