Morph the APIs for Node, ParentNode, and Element closer to the specs

sky/engine/core/dom/ContainerNode.h

Index: sky/engine/core/dom/ContainerNode.h
diff --git a/sky/engine/core/dom/ContainerNode.h b/sky/engine/core/dom/ContainerNode.h
index 3c947b2e98eb92052ab6f130eaa800a3f3e9120f..bc9108d363699bf723c811c6a172e21449a29595 100644
--- a/sky/engine/core/dom/ContainerNode.h
+++ b/sky/engine/core/dom/ContainerNode.h
@@ -43,6 +43,7 @@ const int initialNodeVectorSize = 11;
 typedef Vector<RefPtr<Node>, initialNodeVectorSize> NodeVector;
 
 class ContainerNode : public Node {
+    DEFINE_WRAPPERTYPEINFO();
 public:
     virtual ~ContainerNode();
 
@@ -50,6 +51,21 @@ public:
     Node* lastChild() const { return m_lastChild; }
     bool hasChildren() const { return m_firstChild; }
 
+    Element* firstElementChild() const;

[eseidel, 2015/02/14 00:12:23]

So now ContainerNode knows about its subclass Element? :/

+    Element* lastElementChild() const;
+
+    Vector<RefPtr<Node>> getChildNodes() const;

[eseidel, 2015/02/14 00:12:23]

Are you sure you want to copy the vector? :)

+    Vector<RefPtr<Element>> getChildElements() const;
+
+    // These functions release the nodes from |nodes|.
+    void append(Vector<RefPtr<Node>>& nodes, ExceptionState&);

[eseidel, 2015/02/14 00:12:23]

Another way to do this would be to use a PassOwnPtr<Vector>.  We could also use
an ImplmentedAs=takeFromAndAppend or similar if we wanted to make the c++ naming
more clear.

+    void prepend(Vector<RefPtr<Node>>& nodes, ExceptionState&);
+    PassRefPtr<Node> prependChild(PassRefPtr<Node> node, ExceptionState&);
+
+    void removeChildren();
+    PassRefPtr<Node> setChild(PassRefPtr<Node> node, ExceptionState&);
+    void setChildren(Vector<RefPtr<Node>>& nodes, ExceptionState&);
+
     bool hasOneChild() const { return m_firstChild && !m_firstChild->nextSibling(); }
     bool hasOneTextChild() const { return hasOneChild() && m_firstChild->isTextNode(); }
 
@@ -69,7 +85,6 @@ public:
     // They don't send DOM mutation events or handle reparenting.
     void parserAppendChild(PassRefPtr<Node>);
 
-    void removeChildren();
 
     void cloneChildNodes(ContainerNode* clone);
 
@@ -216,7 +231,7 @@ inline bool Node::isTreeScope() const
     return &treeScope().rootNode() == this;
 }
 
-inline void getChildNodes(ContainerNode& node, NodeVector& nodes)
+inline void appendChildNodes(ContainerNode& node, NodeVector& nodes)
 {
     ASSERT(!nodes.size());
     for (Node* child = node.firstChild(); child; child = child->nextSibling())