Refactor: Wasm return value optimization

[crwen]

Currently, js_sys::Reflect::set is used to convert JsRow to JsValue. It is better to implement it in a more efficient and elegant way.(via stdweb, for example)

tonbolite/src/connection.rs

Lines 215 to 220 in 5ced68a

	for col in row.cols {
	match col.value {
	Value::Null => {
	js_sys::Reflect::set(&object, &col.name.unwrap().into(), &JsValue::null())
	.unwrap();
	}