From 6553e50840b0a0dbf05056a9461f588004d544d3 Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <dg@domgan.com>
Date: Wed, 26 Sep 2018 12:03:57 +0100
Subject: [PATCH 1/4] Ensure addEventListener exists on "window"

---
 packages/scheduler/src/Scheduler.js | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/packages/scheduler/src/Scheduler.js b/packages/scheduler/src/Scheduler.js
index 412f96930eb36..e816cc6ce878a 100644
--- a/packages/scheduler/src/Scheduler.js
+++ b/packages/scheduler/src/Scheduler.js
@@ -573,8 +573,12 @@ if (typeof window === 'undefined') {
     }
   };
   // Assumes that we have addEventListener in this environment. Might need
-  // something better for old IE.
-  window.addEventListener('message', idleTick, false);
+  // something better for old IE. Furthermore, "addEventListener" might not
+  // be available on the window object (if this is a RN mocked window),
+  // so we should check that it's a function before attaching the listener.
+  if (typeof window.addEventListener === 'function') {
+    window.addEventListener('message', idleTick, false);
+  }
 
   var animationTick = function(rafTime) {
     isAnimationFrameScheduled = false;

From f968b8418be7846cb43d71c008c992af5d8cd3d0 Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <dg@domgan.com>
Date: Wed, 26 Sep 2018 12:45:11 +0100
Subject: [PATCH 2/4] Update conditional as per feedback

---
 packages/scheduler/src/Scheduler.js | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/packages/scheduler/src/Scheduler.js b/packages/scheduler/src/Scheduler.js
index e816cc6ce878a..3b2c081511c88 100644
--- a/packages/scheduler/src/Scheduler.js
+++ b/packages/scheduler/src/Scheduler.js
@@ -468,7 +468,9 @@ var requestHostCallback;
 var cancelHostCallback;
 var getFrameDeadline;
 
-if (typeof window === 'undefined') {
+// "addEventListener" might not be available on the window object
+// if this is a mocked "window" object. So we need to validate that too.
+if (typeof window === 'undefined' || typeof window.addEventListener === 'function') {
   // If this accidentally gets imported in a non-browser environment, fallback
   // to a naive implementation.
   var timeoutID = -1;
@@ -573,12 +575,8 @@ if (typeof window === 'undefined') {
     }
   };
   // Assumes that we have addEventListener in this environment. Might need
-  // something better for old IE. Furthermore, "addEventListener" might not
-  // be available on the window object (if this is a RN mocked window),
-  // so we should check that it's a function before attaching the listener.
-  if (typeof window.addEventListener === 'function') {
-    window.addEventListener('message', idleTick, false);
-  }
+  // something better for old IE.
+  window.addEventListener('message', idleTick, false);
 
   var animationTick = function(rafTime) {
     isAnimationFrameScheduled = false;

From 1e99062145c331f0e258c9a6feaebf1cddaee18e Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <dg@domgan.com>
Date: Wed, 26 Sep 2018 12:54:05 +0100
Subject: [PATCH 3/4] fix typo

---
 packages/scheduler/src/Scheduler.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/scheduler/src/Scheduler.js b/packages/scheduler/src/Scheduler.js
index 3b2c081511c88..cfcbc405856c5 100644
--- a/packages/scheduler/src/Scheduler.js
+++ b/packages/scheduler/src/Scheduler.js
@@ -470,7 +470,7 @@ var getFrameDeadline;
 
 // "addEventListener" might not be available on the window object
 // if this is a mocked "window" object. So we need to validate that too.
-if (typeof window === 'undefined' || typeof window.addEventListener === 'function') {
+if (typeof window === 'undefined' || typeof window.addEventListener !== 'function') {
   // If this accidentally gets imported in a non-browser environment, fallback
   // to a naive implementation.
   var timeoutID = -1;

From c35bf9f2aa1add950bd30bebbf0d8e5bfc1ebef8 Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <dg@domgan.com>
Date: Wed, 26 Sep 2018 13:07:45 +0100
Subject: [PATCH 4/4] run prettier

---
 packages/scheduler/src/Scheduler.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/scheduler/src/Scheduler.js b/packages/scheduler/src/Scheduler.js
index cfcbc405856c5..2c692d7dfe79c 100644
--- a/packages/scheduler/src/Scheduler.js
+++ b/packages/scheduler/src/Scheduler.js
@@ -470,7 +470,10 @@ var getFrameDeadline;
 
 // "addEventListener" might not be available on the window object
 // if this is a mocked "window" object. So we need to validate that too.
-if (typeof window === 'undefined' || typeof window.addEventListener !== 'function') {
+if (
+  typeof window === 'undefined' ||
+  typeof window.addEventListener !== 'function'
+) {
   // If this accidentally gets imported in a non-browser environment, fallback
   // to a naive implementation.
   var timeoutID = -1;