Heuristic for capturing SyntheticEvents does not work for minified builds

[jamesdphillips]

form/src/util.js

Lines 325 to 333 in 2d36557

	// Duck-type SyntheticEvent instances
	if (_event !== null && _event !== undefined && typeof _event === 'object') {
	const constructor = _event.constructor;
	if (constructor !== null && constructor !== undefined) {
	const name = constructor.name;
	return /^Synthetic[A-Z]*[a-z]*Event$/.test(name);
	}
	}