[Interpreter] Implement ForIn in bytecode graph builder.

src/interpreter/bytecode-generator.h

Index: src/interpreter/bytecode-generator.h
diff --git a/src/interpreter/bytecode-generator.h b/src/interpreter/bytecode-generator.h
index 35987c46b0236cddef1460adbff7a6c2ca807771..abf288416677641ac84fc36c9dd3c24da6d04378 100644
--- a/src/interpreter/bytecode-generator.h
+++ b/src/interpreter/bytecode-generator.h
@@ -116,6 +116,8 @@ class BytecodeGenerator final : public AstVisitor {
                                   ObjectLiteralProperty* property,
                                   Register value_out);
   void VisitForInAssignment(Expression* expr, FeedbackVectorSlot slot);
+  void GetForInPreparedItem(Register destination, int index,
+                            Register prepare_result, Register scratch);
 
   // Visitors for obtaining expression result in the accumulator, in a
   // register, or just getting the effect.