Remove the Document.charset setter (making it readonly)

Source/core/frame/UseCounter.cpp

 /*
  * Copyright (C) 2012 Google, Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 815 matching lines @@
 
     case CanvasRenderingContext2DCompositeOperationDarker:
         return replacedBy("darker", "darken");
 
     case XMLHttpRequestSynchronousInNonWorkerOutsideBeforeUnload:
         return "Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check http://xhr.spec.whatwg.org/.";
 
     case GetMatchedCSSRules:
         return "'getMatchedCSSRules()' is deprecated. For more help, check https://code.google.com/p/chromium/issues/detail?id=437569#c2";
 
-    case DocumentSetCharset:
-        return "Setting 'Document.charset' is deprecated. Please use '<meta charset=\"UTF-8\">' instead.";
-
     case PrefixedImageSmoothingEnabled:
         return replacedBy("CanvasRenderingContext2D.webkitImageSmoothingEnabled", "CanvasRenderingContext2D.imageSmoothingEnabled");
 
     case AudioListenerDopplerFactor:
         return "dopplerFactor is deprecated and will be removed in M45 when all doppler effects are removed";
 
     case AudioListenerSpeedOfSound:
         return "speedOfSound is deprecated and will be removed in M45 when all doppler effects are removed";
 
     case AudioListenerSetVelocity:
@@ skipping 103 matching lines @@
 UseCounter* UseCounter::getFrom(const StyleSheetContents* sheetContents)
 {
     // FIXME: We may want to handle stylesheets that have multiple owners
     //        http://crbug.com/242125
     if (sheetContents && sheetContents->hasSingleOwnerNode())
         return getFrom(sheetContents->singleOwnerDocument());
     return 0;
 }
 
 } // namespace blink