IDL: Drop redundant null check for string and wrapper 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 51 matching lines @@
         exceptionState.throwIfNeeded();
         return;
     }
     {% endif %}
     {% if attribute.reflect_only %}
     {{release_only_check(attribute.reflect_only, attribute.reflect_missing,
                          attribute.reflect_invalid, attribute.reflect_empty,
                          attribute.cpp_value)
       | indent}}
     {% endif %}
-    {% if attribute.is_nullable %}
-    {% if attribute.is_nullable_simple %}
-    if (!{{attribute.cpp_value}}) {
-    {% else %}
+    {% if attribute.is_nullable and not attribute.is_nullable_simple %}
     if (isNull) {
-    {% endif %}
         v8SetReturnValueNull(info);
         return;
     }
     {% endif %}
     {% if attribute.cached_attribute_validation_method %}
     V8HiddenValue::setHiddenValue(info.GetIsolate(), holder, propertyName, {{attribute.cpp_value_to_v8_value}});
     {% endif %}
     {# v8SetReturnValue #}
     {% if attribute.is_keep_alive_for_gc %}
     if ({{attribute.cpp_value}} && DOMDataStore::setReturnValueFromWrapper{{world_suffix}}<{{attribute.v8_type}}>(info.GetReturnValue(), {{attribute.cpp_value}}.get()))
@@ skipping 220 matching lines @@
     ScriptState* scriptState = ScriptState::from(info.GetIsolate()->GetCurrentContext());
     V8PerContextData* contextData = scriptState->perContextData();
     {% if attribute.activity_logging_world_check %}
     if (scriptState->world().isIsolatedWorld() && contextData && contextData->activityLogger()) {
     {% else %}
     if (contextData && contextData->activityLogger()) {
     {% endif %}
         {% if attribute.activity_logging_include_old_value_for_setter %}
         {{cpp_class}}* impl = {{v8_class}}::toNative(info.Holder());
         {% if attribute.cpp_value_original %}
-        {{attribute.cpp_type}} original = {{attribute.cpp_value_original}};
-        {% else %}
-        {{attribute.cpp_type}} original = {{attribute.cpp_value}};
+        {{attribute.cpp_type}} {{attribute.cpp_value}}({{attribute.cpp_value_original}});
         {% endif %}
         v8::Handle<v8::Value> originalValue = {{attribute.cpp_value_to_v8_value}};
         contextData->activityLogger()->logSetter("{{interface_name}}.{{attribute.name}}", v8Value, originalValue);
         {% else %}
         contextData->activityLogger()->logSetter("{{interface_name}}.{{attribute.name}}", v8Value);
         {% endif %}
     }
     {% endif %}
     {% if attribute.is_custom_element_callbacks or attribute.is_reflect %}
     CustomElementCallbackDispatcher::CallbackDeliveryScope deliveryScope;
     {% 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 %}