IDL compiler: sync Python to r166688 (and clean up special operations+union code)

Source/bindings/templates/methods.cpp

 {##############################################################################}
 {% macro generate_method(method, world_suffix) %}
 {% filter conditional(method.conditional_string) %}
 static void {{method.name}}{{method.overload_index}}Method{{world_suffix}}(const v8::FunctionCallbackInfo<v8::Value>& info)
 {
     {% if method.has_exception_state %}
     ExceptionState exceptionState(ExceptionState::ExecutionContext, "{{method.name}}", "{{interface_name}}", info.Holder(), info.GetIsolate());
     {% endif %}
     {% if method.name in ['addEventListener', 'removeEventListener'] %}
     {{add_remove_event_listener_method(method.name) | indent}}
@@ skipping 183 matching lines @@
     return;
 {% endif %}
 {% if method.is_call_with_script_state %}
 if (state.hadException()) {
     v8::Local<v8::Value> exception = state.exception();
     state.clearException();
     throwError(exception, info.GetIsolate());
     return;
 }
 {% endif %}
-{% if v8_set_return_value %}{{v8_set_return_value}};{% endif %}{# None for void #}
+{% if method.union_arguments %}
+{{union_type_method_call(method)}}
+{% elif v8_set_return_value %}{{v8_set_return_value}};{% endif %}{# None for void #}
 {% endmacro %}
 
+{######################################}
+{% macro union_type_method_call(method) %}
+{% for cpp_type in method.cpp_type %}
+bool result{{loop.index0}}Enabled = false;
+{{cpp_type}} result{{loop.index0}};
+{% endfor %}
+{{method.cpp_value}};
+{% if method.is_null_expression %}{# used by getters #}
+if ({{method.is_null_expression}})
+    return;
+{% endif %}
+{% for v8_set_return_value in method.v8_set_return_value %}
+if (result{{loop.index0}}Enabled) {
+    {{v8_set_return_value}};
+    return;
+}
+{% endfor %}
+{# Fall back to null if none of the union members results are returned #}
+v8SetReturnValueNull(info);
+{%- endmacro %}
+
 
 {######################################}
 {% macro throw_type_error(method, error_message) %}
 {% if method.has_exception_state %}
 exceptionState.throwTypeError({{error_message}});
 exceptionState.throwIfNeeded();
 {%- elif method.is_constructor %}
 throwTypeError(ExceptionMessages::failedToConstruct("{{interface_name}}", {{error_message}}), info.GetIsolate());
 {%- else %}
 throwTypeError(ExceptionMessages::failedToExecute("{{method.name}}", "{{interface_name}}", {{error_message}}), info.GetIsolate());
@@ skipping 184 matching lines @@
     v8::Handle<v8::Object> wrapper = info.Holder();
     {% if is_constructor_raises_exception %}
     if (exceptionState.throwIfNeeded())
         return;
     {% endif %}
 
     V8DOMWrapper::associateObjectWithWrapper<{{v8_class}}>(impl.release(), &{{v8_class}}Constructor::wrapperTypeInfo, wrapper, info.GetIsolate(), WrapperConfiguration::Dependent);
     v8SetReturnValue(info, wrapper);
 }
 {% endmacro %}