Generators return boxed values

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 6403 matching lines @@
   static const int kFunctionOffset = JSObject::kHeaderSize;
   static const int kContextOffset = kFunctionOffset + kPointerSize;
   static const int kReceiverOffset = kContextOffset + kPointerSize;
   static const int kContinuationOffset = kReceiverOffset + kPointerSize;
   static const int kOperandStackOffset = kContinuationOffset + kPointerSize;
   static const int kSize = kOperandStackOffset + kPointerSize;
 
   // Resume mode, for use by runtime functions.
   enum ResumeMode { SEND, THROW };
 
+  // Yielding from a generator returns an object with the following inobject
+  // properties.  See Context::iterator_result_map() for the map.
+  static const int kResultValuePropertyIndex = 0;
+  static const int kResultDonePropertyIndex = 1;
+  static const int kResultPropertyCount = 2;
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSGeneratorObject);
 };
 
 
 // Representation for module instance objects.
 class JSModule: public JSObject {
  public:
   // [context]: the context holding the module's locals, or undefined if none.
   DECL_ACCESSORS(context, Object)
@@ skipping 3091 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_