Add comment to use counter def, so it doesn't constantly get out of sync

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 5451 matching lines @@
     kIntlV8Parse = 14,
     kIntlPattern = 15,
     kIntlResolved = 16,
     kPromiseChain = 17,
     kPromiseAccept = 18,
     kPromiseDefer = 19,
     kHtmlCommentInExternalScript = 20,
     kHtmlComment = 21,
     kSloppyModeBlockScopedFunctionRedefinition = 22,
     kForInInitializer = 23,
+
+    // If you add new values here, you'll also need to update V8Initializer.cpp
+    // in Blink.

[adamk, 2016/02/17 18:56:26]

Maybe this should just say Chromium? Blink isn't really a codebase anymore, just
a project :)

     kUseCounterFeatureCount  // This enum value must be last.
   };
 
   typedef void (*UseCounterCallback)(Isolate* isolate,
                                      UseCounterFeature feature);
 
 
   /**
    * Creates a new isolate.  Does not change the currently entered
    * isolate.
@@ skipping 3053 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // INCLUDE_V8_H_