Support type selector for camel-cased SVG elements in HTML.

Source/core/dom/Element.h

Index: Source/core/dom/Element.h
diff --git a/Source/core/dom/Element.h b/Source/core/dom/Element.h
index 7eb6e4569fd61e548d60539d9e787152bcddb314..5a9b6d0fc6f2e2ee5c14685dcd39ca93f4df2e98 100644
--- a/Source/core/dom/Element.h
+++ b/Source/core/dom/Element.h
@@ -239,6 +239,7 @@ public:
     bool hasLocalName(const AtomicString& other) const { return m_tagName.localName() == other; }
 
     virtual const AtomicString& localName() const override final { return m_tagName.localName(); }
+    AtomicString localNameForSelectorMatching() const;
     const AtomicString& prefix() const { return m_tagName.prefix(); }
     virtual const AtomicString& namespaceURI() const override final { return m_tagName.namespaceURI(); }
 
@@ -846,6 +847,13 @@ inline void Element::setTagNameForCreateElementNS(const QualifiedName& tagName)
     m_tagName = tagName;
 }
 
+inline AtomicString Element::localNameForSelectorMatching() const
+{
+    if (isHTMLElement() || !document().isHTMLDocument())
+        return localName();
+    return localName().lower();
+}
+
 inline bool isShadowHost(const Node* node)
 {
     return node && node->isElementNode() && toElement(node)->shadow();