[WIP] IDL: Add limited serializer support and use for RTCIceCandidate

Source/bindings/templates/methods.cpp

Index: Source/bindings/templates/methods.cpp
diff --git a/Source/bindings/templates/methods.cpp b/Source/bindings/templates/methods.cpp
index 4110a88a37e1ef839ca78d07601d160185c94c70..ad7d1d3d4d8cd252dd361e8aefd819368f628c3a 100644
--- a/Source/bindings/templates/methods.cpp
+++ b/Source/bindings/templates/methods.cpp
@@ -244,7 +244,7 @@ Document& document = *toDocument(currentExecutionContext(info.GetIsolate()));
 if (!{{method.cpp_value}})
     return;
 {% elif method.use_output_parameter_for_result %}
-{{method.cpp_type}} result;
+{{method.cpp_type}} result{{method.cpp_type_initializer}};
 {{cpp_value}};
 {% elif method.is_constructor %}
 {{method.cpp_type}} impl = {{cpp_value}};