Fixing custom element type extensions to have correct native type

Source/bindings/dart/DartCustomElementConstructorBuilder.cpp

Index: Source/bindings/dart/DartCustomElementConstructorBuilder.cpp
diff --git a/Source/bindings/dart/DartCustomElementConstructorBuilder.cpp b/Source/bindings/dart/DartCustomElementConstructorBuilder.cpp
index 0cec8815076954f7ab5dcb1d7bf64f43f50e0b66..fd1aff95f9bb7761b1986e0cd4f50f7cdbe76a4e 100644
--- a/Source/bindings/dart/DartCustomElementConstructorBuilder.cpp
+++ b/Source/bindings/dart/DartCustomElementConstructorBuilder.cpp
@@ -31,11 +31,14 @@
 #include "config.h"
 #include "bindings/dart/DartCustomElementConstructorBuilder.h"
 
+#include "DartHTMLElement.h"
+#include "DartWebkitClassIds.h"
 #include "HTMLNames.h"
 #include "SVGNames.h"
 #include "bindings/dart/DartCustomElementBinding.h"
 #include "bindings/dart/DartCustomElementLifecycleCallbacks.h"
 #include "bindings/dart/DartDOMData.h"
+#include "bindings/dart/DartDOMWrapper.h"
 #include "bindings/dart/DartUtilities.h"
 #include "bindings/v8/V8Binding.h"
 #include "core/dom/CustomElementException.h"
@@ -46,6 +49,7 @@ namespace WebCore {
 DartCustomElementConstructorBuilder::DartCustomElementConstructorBuilder(Dart_Handle customType, const AtomicString& extendsTagName, ScriptState* state, const Dictionary* options)
     : CustomElementConstructorBuilder(state, options)
     , m_customType(customType)
+    , m_nativeClassId(_InvalidClassId)
     , m_extendsTagName(extendsTagName)
     , m_isolate(Dart_CurrentIsolate())
     , m_context(state->context())
@@ -79,11 +83,14 @@ bool DartCustomElementConstructorBuilder::validateOptions(const AtomicString& ty
     if (!m_extendsTagName.isNull() && !m_extendsTagName.isEmpty()) {
         localName = m_extendsTagName.lower();
 
-        if (!DartUtilities::isTypeSubclassOfTag(m_customType, m_extendsTagName)) {
+        Dart_Handle nativeElement = DartUtilities::getAndValidateNativeType(m_customType, m_extendsTagName);
+        if (!nativeElement || Dart_IsNull(nativeElement)) {
             CustomElementException::throwException(CustomElementException::PrototypeDoesNotExtendHTMLElementSVGElementPrototype, type, es);
             return false;
         }
 
+        m_nativeClassId = reinterpret_cast<intptr_t>(DartDOMWrapper::readNativePointer(nativeElement, DartDOMWrapper::kNativeTypeIndex));
+
         // TODO: enable once we pick up Blink version 31
         // if (!Document::isValidName(localName)) {
         //     CustomElementException::throwException(CustomElementException::ExtendsIsInvalidName, type, es);
@@ -95,6 +102,7 @@ bool DartCustomElementConstructorBuilder::validateOptions(const AtomicString& ty
         // }
     } else {
         localName = type;
+        m_nativeClassId = DartHTMLElement::dartClassId;
     }
 
     m_localName = localName;
@@ -127,7 +135,7 @@ bool DartCustomElementConstructorBuilder::createConstructor(Document* document,
 
 bool DartCustomElementConstructorBuilder::didRegisterDefinition(CustomElementDefinition* definition) const
 {
-    return m_callbacks->setBinding(definition, DartCustomElementBinding::create(m_customType));
+    return m_callbacks->setBinding(definition, DartCustomElementBinding::create(m_customType, m_nativeClassId));
 }
 
 ScriptValue DartCustomElementConstructorBuilder::bindingsReturnValue() const