From 2c41d8b44e5ade83c8e5391f4bdcc48e151d4bce Mon Sep 17 00:00:00 2001
From: Sam Lanning <sam@samlanning.com>
Date: Thu, 30 Aug 2018 14:08:24 -0700
Subject: [PATCH] Fix equalOwnProperties

equalOwnProperties would incorrectly report two map-like objects as equal in
the case where a property defined in `left` was not defined in `right` and
whose value was considered "equal" to undefined by the equalityComparer.

This bug was found by an alert on LGTM.com
---
 src/compiler/core.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 1eaab5b1b59..d5caadf079a 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -1272,7 +1272,7 @@ namespace ts {
         if (!left || !right) return false;
         for (const key in left) {
             if (hasOwnProperty.call(left, key)) {
-                if (!hasOwnProperty.call(right, key) === undefined) return false;
+                if (!hasOwnProperty.call(right, key)) return false;
                 if (!equalityComparer(left[key], right[key])) return false;
             }
         }