Generator objects can suspend

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index d20eba58fc91117e4bac2bd39898905b1c25cd3c..7d1318904adac15029e79b97a2d1e177c7abf643 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -6264,10 +6264,13 @@ class JSGeneratorObject: public JSObject {
   // [function]: The function corresponding to this generator object.
   DECL_ACCESSORS(function, JSFunction)
 
-  // [context]: The context of the suspended computation, or undefined.
-  DECL_ACCESSORS(context, Object)
+  // [context]: The context of the suspended computation.
+  DECL_ACCESSORS(context, Context)
 
   // [continuation]: Offset into code of continuation.
+  //
+  // The sign of the offset corresponds to the generator state: positive is
+  // "suspended", negative is "executing" and 0 is "closed".
   inline int continuation();
   inline void set_continuation(int continuation);