Introduce isHTMLTableElement and toHTMLTableElement

Source/core/html/HTMLTableElement.h

Index: Source/core/html/HTMLTableElement.h
diff --git a/Source/core/html/HTMLTableElement.h b/Source/core/html/HTMLTableElement.h
index 73fee6b42a9366b6bcd31bc727f9fcfbff526897..c9b4afd381ca56140d1d21d84308a4454164f552 100644
--- a/Source/core/html/HTMLTableElement.h
+++ b/Source/core/html/HTMLTableElement.h
@@ -100,6 +100,22 @@ private:
     RefPtr<StylePropertySet> m_sharedCellStyle;
 };
 
+inline bool isHTMLTableElement(const Node* node)
+{
+    return node->hasTagName(HTMLNames::tableTag);
+}
+
+inline bool isHTMLTableElement(const Element* element)
+{
+    return element->hasTagName(HTMLNames::tableTag);
+}
+
+inline HTMLTableElement* toHTMLTableElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || isHTMLTableElement(node));
+    return static_cast<HTMLTableElement*>(node);
+}
+
 } //namespace
 
 #endif