CHECK that FunctionTemplates are not modified after first instantiation

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 5658c8f0acef3e8d676aa30aee750984ee21f31b..d0a6e333d1747664d00bd1189b47811436697de6 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -10607,6 +10607,7 @@ class FunctionTemplateInfo: public TemplateInfo {
   DECL_BOOLEAN_ACCESSORS(read_only_prototype)
   DECL_BOOLEAN_ACCESSORS(remove_prototype)
   DECL_BOOLEAN_ACCESSORS(do_not_cache)
+  DECL_BOOLEAN_ACCESSORS(instantiated)
 
   DECLARE_CAST(FunctionTemplateInfo)
 
@@ -10647,6 +10648,7 @@ class FunctionTemplateInfo: public TemplateInfo {
   static const int kReadOnlyPrototypeBit = 3;
   static const int kRemovePrototypeBit   = 4;
   static const int kDoNotCacheBit        = 5;
+  static const int kInstantiatedBit      = 6;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(FunctionTemplateInfo);
 };