DOM: adoptNode() should not crash by reparenting the specified node in removeChild().

third_party/WebKit/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.
@@ skipping 1164 matching lines @@
           exceptionState.throwDOMException(
               HierarchyRequestError,
               "The node provided is a frame which contains this document.");
           return nullptr;
         }
       }
       if (source->parentNode()) {
         source->parentNode()->removeChild(source, exceptionState);
         if (exceptionState.hadException())
           return nullptr;
-        CHECK(!source->parentNode());
+        // The above removeChild() can execute arbitrary JavaScript code.
+        if (source->parentNode()) {
+          addConsoleMessage(ConsoleMessage::create(
+              JSMessageSource, WarningMessageLevel,
+              ExceptionMessages::failedToExecute("adoptNode", "Document",
+                                                 "Unable to remove the "
+                                                 "specified node from the "
+                                                 "original parent.")));
+          return nullptr;
+        }
       }
   }
 
   this->adoptIfNeeded(*source);
 
   return source;
 }
 
 bool Document::hasValidNamespaceForElements(const QualifiedName& qName) {
   // These checks are from DOM Core Level 2, createElementNS
@@ skipping 5482 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (blink::Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->url().getString().utf8().data());
 }
 #endif