Reland "Prevent liveedit on or under generators with open activations"

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 12f2ee0e5ce980e9009a80d944bb30a92a2b3828..b46401365bdf6dee639b8bfdc1924f70b4233ef9 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -7460,6 +7460,8 @@ class JSGeneratorObject: public JSObject {
   // cannot be resumed.
   inline int continuation();
   inline void set_continuation(int continuation);
+  inline bool is_closed();
+  inline bool is_executing();
   inline bool is_suspended();
 
   // [operand_stack]: Saved operand stack.