Not documented.
Source
convertDartToNative_Dictionary(Map dict) {
if (dict == null) return null;
var jsObject = new js.JsObject(js.context['Object']);
dict.forEach((String key, value) {
if (value is List) {
var jsArray = new js.JsArray();
value.forEach((elem) {
jsArray.add(elem is Map ? convertDartToNative_Dictionary(elem): elem);
});
jsObject[key] = jsArray;
} else {
jsObject[key] = value;
}
});
return jsObject;
}