From c5e144f327e7990853f2623f05562d877e133058 Mon Sep 17 00:00:00 2001
From: Steven Degutis <sbdegutis@gmail.com>
Date: Fri, 6 Dec 2019 15:57:26 -0600
Subject: [PATCH] Avoid roundtrip to browser when double-disposing.

---
 src/browser/Lifecycle.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/browser/Lifecycle.ts b/src/browser/Lifecycle.ts
index 1344ea9b..a8172db5 100644
--- a/src/browser/Lifecycle.ts
+++ b/src/browser/Lifecycle.ts
@@ -17,12 +17,13 @@ export function addDisposableDomListener(
   useCapture?: boolean
 ): IDisposable {
   node.addEventListener(type, handler, useCapture);
+  let disposed = false;
   return {
     dispose: () => {
-      if (!handler) {
-        // Already disposed
+      if (!disposed) {
         return;
       }
+      disposed = true;
       node.removeEventListener(type, handler, useCapture);
     }
   };