[API] remove (deprecated) hidden properties.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 83b777d30948104bec43ba3c9926cd68ff637690..bfdf039ae597830f3f9f5f8bbd243e830308b494 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -2965,13 +2965,6 @@ class V8_EXPORT Object : public Value {
    */
   int GetIdentityHash();
 
-  V8_DEPRECATED("Use v8::Object::SetPrivate instead.",
-                bool SetHiddenValue(Local<String> key, Local<Value> value));
-  V8_DEPRECATED("Use v8::Object::GetPrivate instead.",
-                Local<Value> GetHiddenValue(Local<String> key));
-  V8_DEPRECATED("Use v8::Object::DeletePrivate instead.",
-                bool DeleteHiddenValue(Local<String> key));
-
   /**
    * Clone this object with a fast but shallow copy.  Values will point
    * to the same values as the original object.