add some babel stuff

node_modules/es-abstract/helpers/assign.js

@@ -0,0 +1,12 @@
+var has = Object.prototype.hasOwnProperty;
+module.exports = function assign(target, source) {
+	if (Object.assign) {
+		return Object.assign(target, source);
+	}
+	for (var key in source) {
+		if (has.call(source, key)) {
+			target[key] = source[key];
+		}
+	}
+	return target;
+};