Fix StrictTypeChecking on interface type attributes

Source/bindings/templates/attributes.cpp

 {##############################################################################}
 {% macro attribute_getter(attribute, world_suffix) %}
 {% filter conditional(attribute.conditional_string) %}
 static void {{attribute.name}}AttributeGetter{{world_suffix}}(
 {%- if attribute.is_expose_js_accessors %}
 const v8::FunctionCallbackInfo<v8::Value>& info
 {%- else %}
 const v8::PropertyCallbackInfo<v8::Value>& info
 {%- endif %})
 {
@@ skipping 33 matching lines @@
         return;
     {% endif %}
     {# Local variables #}
     {% if attribute.is_call_with_execution_context %}
     ExecutionContext* scriptContext = currentExecutionContext(info.GetIsolate());
     {% endif %}
     {% if attribute.is_check_security_for_node or
           attribute.is_getter_raises_exception %}
     ExceptionState exceptionState(ExceptionState::GetterContext, "{{attribute.name}}", "{{interface_name}}", holder, info.GetIsolate());
     {% endif %}
-    {% if attribute.is_nullable %}
+    {% if attribute.is_nullable and not attribute.has_strict_type_checking %}
     bool isNull = false;
     {% endif %}
     {# FIXME: consider always using a local variable for value #}
     {% if attribute.cached_attribute_validation_method or
           attribute.is_getter_raises_exception or
           attribute.is_nullable or
           attribute.reflect_only or
           attribute.idl_type == 'EventHandler' %}
     {{attribute.cpp_type}} {{attribute.cpp_value}} = {{attribute.cpp_value_original}};
     {% endif %}
     {# Checks #}
     {% if attribute.is_getter_raises_exception %}
     if (UNLIKELY(exceptionState.throwIfNeeded()))
         return;
     {% endif %}
     {% if attribute.is_check_security_for_node %}
     {# FIXME: use a local variable to not call getter twice #}
     if (!BindingSecurity::shouldAllowAccessToNode(info.GetIsolate(), {{attribute.cpp_value}}, exceptionState)) {
         v8SetReturnValueNull(info);
         exceptionState.throwIfNeeded();
         return;
     }
     {% endif %}
     {% if attribute.reflect_only %}
     {{release_only_check(attribute.reflect_only, attribute.reflect_missing,
                          attribute.reflect_invalid, attribute.reflect_empty)
       | indent}}
     {% endif %}
     {% if attribute.is_nullable %}
+    {% if attribute.has_strict_type_checking %}
+    if (!{{attribute.cpp_value}}) {
+    {% else %}
     if (isNull) {
+    {% endif %}
         v8SetReturnValueNull(info);
         return;
     }
     {% endif %}
     {% if attribute.cached_attribute_validation_method %}
     V8HiddenValue::setHiddenValue(info.GetIsolate(), holder, propertyName, {{attribute.cpp_value}}.v8Value());
     {% endif %}
     {# v8SetReturnValue #}
     {% if attribute.is_keep_alive_for_gc %}
     {# FIXME: merge local variable assignment with above #}
@@ skipping 118 matching lines @@
     {% if not attribute.is_static %}
     v8::Handle<v8::Object> holder = info.Holder();
     {% endif %}
     {% if attribute.has_setter_exception_state %}
     ExceptionState exceptionState(ExceptionState::SetterContext, "{{attribute.name}}", "{{interface_name}}", holder, info.GetIsolate());
     {% endif %}
     {# Type checking #}
     {% if attribute.has_strict_type_checking %}
     {# Type checking for interface types (if interface not implemented, throw
        TypeError), per http://www.w3.org/TR/WebIDL/#es-interface #}
-    if (!isUndefinedOrNull(v8Value) && !V8{{attribute.idl_type}}::hasInstance(v8Value, info.GetIsolate())) {
+    if ({% if attribute.is_nullable %}!isUndefinedOrNull(v8Value) && {% endif %}!V8{{attribute.idl_type}}::hasInstance(v8Value, info.GetIsolate())) {
         exceptionState.throwTypeError("The provided value is not of type '{{attribute.idl_type}}'.");
         exceptionState.throwIfNeeded();
         return;
     }
     {% endif %}
     {# impl #}
     {% if attribute.put_forwards %}
     {{cpp_class}}* proxyImpl = {{v8_class}}::toNative(holder);
     {{attribute.ref_ptr}}<{{attribute.idl_type}}> impl = WTF::getPtr(proxyImpl->{{attribute.name}}());
     if (!impl)
@@ skipping 77 matching lines @@
     {% endif %}
     {% if attribute.has_custom_setter %}
     {{v8_class}}::{{attribute.name}}AttributeSetterCustom(v8Value, info);
     {% else %}
     {{cpp_class}}V8Internal::{{attribute.name}}AttributeSetter{{world_suffix}}(v8Value, info);
     {% endif %}
     TRACE_EVENT_SET_SAMPLING_STATE("V8", "V8Execution");
 }
 {% endfilter %}
 {% endmacro %}