Calling a generator function returns a generator object

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index f8afdbcc79572899f249f5abb708d2f096ec3f42..cdbb0b90a6d3e7810d6d6dc07097c86a1ae192cd 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -62,6 +62,7 @@
 //           - JSWeakMap
 //           - JSRegExp
 //           - JSFunction
+//           - JSGeneratorIterator
 //           - JSModule
 //           - GlobalObject
 //             - JSGlobalObject
@@ -395,6 +396,7 @@ const int kStubMinorKeyBits = kBitsPerInt - kSmiTagSize - kStubMajorKeyBits;
   V(JS_DATE_TYPE)                                                              \
   V(JS_OBJECT_TYPE)                                                            \
   V(JS_CONTEXT_EXTENSION_OBJECT_TYPE)                                          \
+  V(JS_GENERATOR_ITERATOR_TYPE)                                                \
   V(JS_MODULE_TYPE)                                                            \
   V(JS_GLOBAL_OBJECT_TYPE)                                                     \
   V(JS_BUILTINS_OBJECT_TYPE)                                                   \
@@ -726,6 +728,7 @@ enum InstanceType {
   JS_DATE_TYPE,
   JS_OBJECT_TYPE,
   JS_CONTEXT_EXTENSION_OBJECT_TYPE,
+  JS_GENERATOR_ITERATOR_TYPE,
   JS_MODULE_TYPE,
   JS_GLOBAL_OBJECT_TYPE,
   JS_BUILTINS_OBJECT_TYPE,
@@ -953,6 +956,7 @@ class MaybeObject BASE_EMBEDDED {
   V(JSReceiver)                                \
   V(JSObject)                                  \
   V(JSContextExtensionObject)                  \
+  V(JSGeneratorIterator)                       \
   V(JSModule)                                  \
   V(Map)                                       \
   V(DescriptorArray)                           \
@@ -6238,6 +6242,41 @@ class SharedFunctionInfo: public HeapObject {
 };
 
 
+// Representation for generator iterators.
+class JSGeneratorIterator: public JSObject {
+ public:
+  // [function]: The function corresponding to this iterator.
+  DECL_ACCESSORS(function, JSFunction)
+
+  // [context]: The context of the suspended computation, or Smi 0.
+  DECL_ACCESSORS(context, Object)
+
+  // [continuation]: Offset into code of continuation.
+  inline int continuation();
+  inline void set_continuation(int continuation);
+
+  // [operands]: Saved operand stack: FixedArray or Smi 0.
+  DECL_ACCESSORS(operand_stack, Object)
+
+  // Casting.
+  static inline JSGeneratorIterator* cast(Object* obj);
+
+  // Dispatched behavior.
+  DECLARE_PRINTER(JSGeneratorIterator)
+  DECLARE_VERIFIER(JSGeneratorIterator)
+
+  // Layout description.
+  static const int kFunctionOffset = JSObject::kHeaderSize;
+  static const int kContextOffset = kFunctionOffset + kPointerSize;
+  static const int kContinuationOffset = kContextOffset + kPointerSize;
+  static const int kOperandStackOffset = kContinuationOffset + kPointerSize;
+  static const int kSize = kOperandStackOffset + kPointerSize;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSGeneratorIterator);
+};
+
+
 // Representation for module instance objects.
 class JSModule: public JSObject {
  public: