Remove custom element type extensions.

sky/engine/core/dom/Element.cpp

Index: sky/engine/core/dom/Element.cpp
diff --git a/sky/engine/core/dom/Element.cpp b/sky/engine/core/dom/Element.cpp
index 171c4d084b9439d3154cc21322541323f15e4403..5b5e69c55d6b4fa459a315012b35aa2390eed029 100644
--- a/sky/engine/core/dom/Element.cpp
+++ b/sky/engine/core/dom/Element.cpp
@@ -677,8 +677,6 @@ void Element::attributeChanged(const QualifiedName& name, const AtomicString& ne
 
 inline void Element::attributeChangedFromParserOrByCloning(const QualifiedName& name, const AtomicString& newValue, AttributeModificationReason reason)
 {
-    if (name == HTMLNames::isAttr)
-        CustomElementRegistrationContext::setTypeExtension(this, newValue);
     attributeChanged(name, newValue, reason);
 }