Throw DOMException when invoked Document::execCommand on non-{X,}HTML documents

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 4231 matching lines @@
     LocalFrame* frame = document->frame();
     if (!frame || frame->document() != document)
         return Editor::Command();
 
     document->updateLayoutTreeIfNeeded();
     return frame->editor().command(commandName, CommandFromDOM);
 }
 
 bool Document::execCommand(const String& commandName, bool, const String& value)
 {
+    if (!isHTMLDocument() && !isXHTMLDocument())
+        return false;
+
     // We don't allow recursive |execCommand()| to protect against attack code.
     // Recursive call of |execCommand()| could be happened by moving iframe
     // with script triggered by insertion, e.g. <iframe src="javascript:...">
     // <iframe onload="...">. This usage is valid as of the specification
     // although, it isn't common use case, rather it is used as attack code.
     static bool inExecCommand = false;
     if (inExecCommand) {
         String message = "We don't execute document.execCommand() this time, because it is called recursively.";
         addConsoleMessage(ConsoleMessage::create(JSMessageSource, WarningMessageLevel, message));
         return false;
@@ skipping 1420 matching lines @@
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().string().utf8().data());
 }
 #endif