Remove duplicate way of encoding the holder in the flags.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index b58b0b3ed10f3ce90756835a2a49a31b52749739..23f11e1a9d60b5938754789ab0bef1a47c93b822 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4810,11 +4810,6 @@ class Code: public HeapObject {
     NONEXISTENT
   };
 
-  enum StubHolder {
-    OWN_STUB,
-    PROTOTYPE_STUB
-  };
-
   typedef int ExtraICState;
 
   static const ExtraICState kNoExtraICState = 0;
@@ -5019,8 +5014,6 @@ class Code: public HeapObject {
   class ExtraICStateKeyedAccessStoreMode:
       public BitField<KeyedAccessStoreMode, 1, 4> {};  // NOLINT
 
-  class ExtraICStateStubHolder: public BitField<StubHolder, 0, 1> {};
-
   static inline StrictModeFlag GetStrictMode(ExtraICState extra_ic_state) {
     return ExtraICStateStrictMode::decode(extra_ic_state);
   }
@@ -5037,10 +5030,6 @@ class Code: public HeapObject {
         ExtraICStateStrictMode::encode(strict_mode);
   }
 
-  static inline ExtraICState ComputeExtraICState(StubHolder stub_holder) {
-    return ExtraICStateStubHolder::encode(stub_holder);
-  }
-
   // Flags operations.
   static inline Flags ComputeFlags(
       Kind kind,