in gr-editor/gr-editor.js [60:71]
const loadListener = function(event) {
cleanup();
// In case of a successful load, cache the load event on the link so
// that it can be used to short-circuit this method in the future when
// it is called with the same href param.
link.__dynamicImportLoaded = true;
if (onload) {
whenImportsReady(() => {
onload(event);
});
}
};