IDL: Further improve indexed/named property setter type checking

Source/bindings/templates/interface.cpp

 {% extends 'interface_base.cpp' %}
 
 
 {##############################################################################}
 {% block indexed_property_getter %}
 {% if indexed_property_getter and not indexed_property_getter.is_custom %}
 {% set getter = indexed_property_getter %}
 static void indexedPropertyGetter(uint32_t index, const v8::PropertyCallbackInfo<v8::Value>& info)
 {
     {{cpp_class}}* impl = {{v8_class}}::toImpl(info.Holder());
@@ skipping 43 matching lines @@
 static void indexedPropertySetter(uint32_t index, v8::Local<v8::Value> v8Value, const v8::PropertyCallbackInfo<v8::Value>& info)
 {
     {{cpp_class}}* impl = {{v8_class}}::toImpl(info.Holder());
     {{setter.v8_value_to_local_cpp_value}};
     {% if setter.has_exception_state %}
     ExceptionState exceptionState(ExceptionState::IndexedSetterContext, "{{interface_name}}", info.Holder(), info.GetIsolate());
     {% endif %}
     {% if setter.has_type_checking_interface %}
     {# Type checking for interface types (if interface not implemented, throw
        TypeError), per http://www.w3.org/TR/WebIDL/#es-interface #}
-    if (!isUndefinedOrNull(v8Value) && !V8{{setter.idl_type}}::hasInstance(v8Value, info.GetIsolate())) {
+    if (!propertyValue{% if setter.is_nullable %} && !isUndefinedOrNull(v8Value){% endif %}) {
         exceptionState.throwTypeError("The provided value is not of type '{{setter.idl_type}}'.");
         exceptionState.throwIfNeeded();
         return;
     }
     {% endif %}
     {% set setter_name = setter.name or 'anonymousIndexedSetter' %}
     {% set setter_arguments = ['index', 'propertyValue', 'exceptionState']
            if setter.is_raises_exception else ['index', 'propertyValue'] %}
     bool result = impl->{{setter_name}}({{setter_arguments | join(', ')}});
     {% if setter.is_raises_exception %}
@@ skipping 150 matching lines @@
 
     {% endif %}
     {% if setter.has_exception_state %}
     v8::String::Utf8Value namedProperty(nameString);
     ExceptionState exceptionState(ExceptionState::SetterContext, *namedProperty, "{{interface_name}}", info.Holder(), info.GetIsolate());
     {% endif %}
     {{cpp_class}}* impl = {{v8_class}}::toImpl(info.Holder());
     {# v8_value_to_local_cpp_value('DOMString', 'nameString', 'propertyName') #}
     TOSTRING_VOID(V8StringResource<>, propertyName, nameString);
     {{setter.v8_value_to_local_cpp_value}};
+    {% if setter.has_type_checking_interface %}
+    {# Type checking for interface types (if interface not implemented, throw
+       TypeError), per http://www.w3.org/TR/WebIDL/#es-interface #}
+    if (!propertyValue{% if setter.is_nullable %} && !isUndefinedOrNull(v8Value){% endif %}) {
+        exceptionState.throwTypeError("The provided value is not of type '{{setter.idl_type}}'.");
+        exceptionState.throwIfNeeded();
+        return;
+    }
+    {% endif %}
     {% set setter_name = setter.name or 'anonymousNamedSetter' %}
     {% set setter_arguments =
            ['propertyName', 'propertyValue', 'exceptionState']
            if setter.is_raises_exception else
            ['propertyName', 'propertyValue'] %}
     bool result = impl->{{setter_name}}({{setter_arguments | join(', ')}});
     {% if setter.is_raises_exception %}
     if (exceptionState.throwIfNeeded())
         return;
     {% endif %}
@@ skipping 725 matching lines @@
 }
 
 {% for method in methods if method.overloads and method.overloads.has_partial_overloads %}
 void {{v8_class}}::register{{method.name | blink_capitalize}}MethodForPartialInterface(void (*method)(const v8::FunctionCallbackInfo<v8::Value>&))
 {
     {{cpp_class}}V8Internal::{{method.name}}MethodForPartialInterface = method;
 }
 {% endfor %}
 {% endif %}
 {% endblock %}