fix bad def

dedupe.js

@@ -69,7 +69,7 @@ const classNames = (function () {
 		// don't leak arguments
 		// https://github.com/petkaantonov/bluebird/wiki/Optimization-killers#32-leaking-arguments
 		const length = arguments.length;
-		const args = Array(len);
+		const args = Array(length);
 		for (let i = 0; i < length; i++) {
 			args[i] = arguments[i];
 		}