[Interpreter] Implement ForInStep directly.

src/compiler/code-stub-assembler.h

 // 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.
 
 #ifndef V8_COMPILER_CODE_STUB_ASSEMBLER_H_
 #define V8_COMPILER_CODE_STUB_ASSEMBLER_H_
 
 #include <map>
 
 // Clients of this interface shouldn't depend on lots of compiler internals.
@@ skipping 85 matching lines @@
   };
 
   // ===========================================================================
   // Base Assembler
   // ===========================================================================
 
   // Constants.
   Node* Int32Constant(int value);
   Node* IntPtrConstant(intptr_t value);
   Node* NumberConstant(double value);
+  Node* SmiConstant(Smi* value);
   Node* HeapConstant(Handle<HeapObject> object);
   Node* BooleanConstant(bool value);
   Node* ExternalConstant(ExternalReference address);
 
   Node* Parameter(int value);
   void Return(Node* value);
 
   void Bind(Label* label);
   void Goto(Label* label);
   void Branch(Node* condition, Label* true_label, Label* false_label);
@@ skipping 72 matching lines @@
                  Node** args, size_t result_size = 1);
 
   // ===========================================================================
   // Macros
   // ===========================================================================
 
   // Tag and untag Smi values.
   Node* SmiTag(Node* value);
   Node* SmiUntag(Node* value);
 
+  // Smi operations.
+  Node* SmiAdd(Node* lhs, Node* rhs);
+
   // Load a value from the root array.
   Node* LoadRoot(Heap::RootListIndex root_index);
 
   // Check a value for smi-ness
   Node* WordIsSmi(Node* a);
 
   // Load an object pointer from a buffer that isn't in the heap.
   Node* LoadBufferObject(Node* buffer, int offset);
   // Load a field from an object on the heap.
   Node* LoadObjectField(Node* object, int offset);
@@ skipping 55 matching lines @@
   // Map of variables to the list of value nodes that have been added from each
   // merge path in their order of merging.
   std::map<Variable::Impl*, std::vector<Node*>> variable_merges_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_CODE_STUB_ASSEMBLER_H_