From 992bc88800f20fed588e08fdff259448f06651fe Mon Sep 17 00:00:00 2001
From: kzc <zaxxon2011@gmail.com>
Date: Sun, 17 Dec 2017 21:21:05 -0500
Subject: [PATCH] fix slowness in `unused` for blocks

---
 lib/compress.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/compress.js b/lib/compress.js
index 4065c543..59307905 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -2827,6 +2827,7 @@ merge(Compressor.prototype, {
                     if (in_list && all(node.body, can_be_evicted_from_block)) {
                         return MAP.splice(node.body);
                     }
+                    return node;
                 }
                 if (node instanceof AST_Scope) {
                     var save_scope = scope;