Fixing custom element type extensions to have correct native type

Source/bindings/dart/DartCustomElementWrapper.cpp

Index: Source/bindings/dart/DartCustomElementWrapper.cpp
diff --git a/Source/bindings/dart/DartCustomElementWrapper.cpp b/Source/bindings/dart/DartCustomElementWrapper.cpp
index 569c7bfd8ae584d4a3d4665fadeb69299708458b..1634eb39ced61adbf66efaa4690603f25778d905 100644
--- a/Source/bindings/dart/DartCustomElementWrapper.cpp
+++ b/Source/bindings/dart/DartCustomElementWrapper.cpp
@@ -114,8 +114,7 @@ Dart_Handle DartCustomElementWrapper<HTMLElement>::upgradeDartWrapper(HTMLElemen
 
     Dart_Handle newInstance = Dart_Allocate(customType);
     ASSERT(!Dart_IsError(newInstance));
-    // TODO(14190): Use a more specific type instead of DartHTMLElement here.
-    DartDOMWrapper::writeNativePointer(newInstance, element, DartHTMLElement::dartClassId);
+    DartDOMWrapper::writeNativePointer(newInstance, element, binding->nativeClassId());
 
     Dart_Handle result = Dart_InvokeConstructor(newInstance, Dart_NewStringFromCString("created"), 0, 0);
 
@@ -134,8 +133,7 @@ Dart_Handle DartCustomElementWrapper<HTMLElement>::upgradeDartWrapper(HTMLElemen
         Dart_Handle fallbackWrapper = createUpgradeCandidateWrapper(element, createSpecificWrapper);
 
         DartDOMWrapper::associateWrapper<DartHTMLElement>(domData, element, fallbackWrapper);
-        // TODO(14190): Use a more specific type instead of DartHTMLElement here.
-        DartDOMWrapper::writeNativePointer(fallbackWrapper, element, DartHTMLElement::dartClassId);
+        DartDOMWrapper::writeNativePointer(fallbackWrapper, element, binding->nativeClassId());
         return fallbackWrapper;
     }
     return newInstance;