Make classes and structures in core/html fast-allocated.

Source/core/html/HTMLElement.h

Index: Source/core/html/HTMLElement.h
diff --git a/Source/core/html/HTMLElement.h b/Source/core/html/HTMLElement.h
index 7a7ec1d1b6a8a95ee8643344bec1cb15d0d73da3..333cd66b1808d4416ff7701a2e3a81c858236f4d 100644
--- a/Source/core/html/HTMLElement.h
+++ b/Source/core/html/HTMLElement.h
@@ -159,6 +159,7 @@ inline bool Node::hasTagName(const HTMLQualifiedName& name) const
 
 // Functor used to match HTMLElements with a specific HTML tag when using the ElementTraversal API.
 class HasHTMLTagName {
+    STACK_ALLOCATED();
 public:
     explicit HasHTMLTagName(const HTMLQualifiedName& tagName): m_tagName(tagName) { }
     bool operator() (const HTMLElement& element) const { return element.hasTagName(m_tagName); }