Be more strict about multiple documentElements

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 3240 matching lines @@
         // Documents may contain no more than one of each of these.
         // (One Element and one DocumentType.)
         for (Node& c : NodeTraversal::childrenOf(*this))
             if (c.nodeType() == type)
                 return false;
         return true;
     }
     return false;
 }
 
-bool Document::canReplaceChild(const Node& newChild, const Node& oldChild) const
+bool Document::canAcceptChild(const Node& newChild, const Node* oldChild, ExceptionState& exceptionState) const
 {
-    if (oldChild.nodeType() == newChild.nodeType())
+    if (oldChild && oldChild->nodeType() == newChild.nodeType())
         return true;
 
     int numDoctypes = 0;
     int numElements = 0;
 
     // First, check how many doctypes and elements we have, not counting
     // the child we're about to remove.
-    for (Node& c : NodeTraversal::childrenOf(*this)) {
-        if (c == oldChild)
+    for (Node& child : NodeTraversal::childrenOf(*this)) {
+        if (oldChild && *oldChild == child)
             continue;
 
-        switch (c.nodeType()) {
+        switch (child.nodeType()) {
         case DOCUMENT_TYPE_NODE:
             numDoctypes++;
             break;
         case ELEMENT_NODE:
             numElements++;
             break;
         default:
             break;
         }
     }
 
     // Then, see how many doctypes and elements might be added by the new child.
     if (newChild.isDocumentFragment()) {
-        for (Node& c : NodeTraversal::childrenOf(toDocumentFragment(newChild))) {
-            switch (c.nodeType()) {
+        for (Node& child : NodeTraversal::childrenOf(toDocumentFragment(newChild))) {
+            switch (child.nodeType()) {
             case ATTRIBUTE_NODE:
             case CDATA_SECTION_NODE:
             case DOCUMENT_FRAGMENT_NODE:
             case DOCUMENT_NODE:
             case TEXT_NODE:
+                exceptionState.throwDOMException(HierarchyRequestError, "Nodes of type '" + newChild.nodeName() +
+                    "' may not be inserted inside nodes of type '#document'.");
                 return false;
             case COMMENT_NODE:
             case PROCESSING_INSTRUCTION_NODE:
                 break;
             case DOCUMENT_TYPE_NODE:
                 numDoctypes++;
                 break;
             case ELEMENT_NODE:
                 numElements++;
                 break;
             }
         }
     } else {
         switch (newChild.nodeType()) {
         case ATTRIBUTE_NODE:
         case CDATA_SECTION_NODE:
         case DOCUMENT_FRAGMENT_NODE:
         case DOCUMENT_NODE:
         case TEXT_NODE:
+            exceptionState.throwDOMException(HierarchyRequestError, "Nodes of type '" + newChild.nodeName() +
+                "' may not be inserted inside nodes of type '#document'.");
             return false;
         case COMMENT_NODE:
         case PROCESSING_INSTRUCTION_NODE:
             return true;
         case DOCUMENT_TYPE_NODE:
             numDoctypes++;
             break;
         case ELEMENT_NODE:
             numElements++;
             break;
         }
     }
 
-    if (numElements > 1 || numDoctypes > 1)
+    if (numElements > 1 || numDoctypes > 1) {
+        exceptionState.throwDOMException(HierarchyRequestError,
+            String::format("Only one %s on document allowed.",
+            numElements > 1 ? "element" : "doctype"));
         return false;
+    }
 
     return true;
 }
 
 PassRefPtrWillBeRawPtr<Node> Document::cloneNode(bool deep)
 {
     RefPtrWillBeRawPtr<Document> clone = cloneDocumentWithoutChildren();
     clone->cloneDataFromDocument(*this);
     if (deep)
         cloneChildNodes(clone.get());
@@ skipping 2499 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