From 3269d4c928ef0d8310c2f57634e9b6057aa636e9 Mon Sep 17 00:00:00 2001
From: Kagami Sascha Rosylight <krosylight@mozilla.com>
Date: Wed, 6 Apr 2022 11:57:57 +0000
Subject: [PATCH] Bug 1703953 - Part 3: Apply mozilla/use-isInstance to
 devtools r=julienw

Differential Revision: https://phabricator.services.mozilla.com/D142068
---
 devtools/client/performance-new/@types/gecko.d.ts   |  8 ++++++++
 .../client/performance-new/symbolication.jsm.js     | 13 +++----------
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/devtools/client/performance-new/@types/gecko.d.ts b/devtools/client/performance-new/@types/gecko.d.ts
index 5cded8f68b85..6bab9780b7f6 100644
--- a/devtools/client/performance-new/@types/gecko.d.ts
+++ b/devtools/client/performance-new/@types/gecko.d.ts
@@ -486,3 +486,11 @@ declare interface XULElementWithCommandHandler {
 }
 
 declare type nsIPrefBranch = MockedExports.nsIPrefBranch;
+
+// chrome context-only DOM isInstance method
+// XXX: This hackishly extends Function because there is no way to extend DOM constructors.
+// Callers should manually narrow the type when needed.
+// See also https://github.com/microsoft/TypeScript-DOM-lib-generator/issues/222
+interface Function {
+  isInstance(obj: any): boolean;
+}
diff --git a/devtools/client/performance-new/symbolication.jsm.js b/devtools/client/performance-new/symbolication.jsm.js
index 9765835f99d8..b2535b484b71 100644
--- a/devtools/client/performance-new/symbolication.jsm.js
+++ b/devtools/client/performance-new/symbolication.jsm.js
@@ -139,7 +139,7 @@ async function getResultFromWorker(workerURL, initialMessageToWorker) {
     worker.onerror = errorEvent => {
       gActiveWorkers.delete(worker);
       worker.terminate();
-      if (errorEvent instanceof ErrorEvent) {
+      if (ErrorEvent.isInstance(errorEvent)) {
         const { message, filename, lineno } = errorEvent;
         const error = new Error(`${message} at ${filename}:${lineno}`);
         error.name = "WorkerError";
@@ -152,17 +152,10 @@ async function getResultFromWorker(workerURL, initialMessageToWorker) {
     // Handle errors from messages that cannot be deserialized. I'm not sure
     // how to get into such a state, but having this handler seems like a good
     // idea.
-    worker.onmessageerror = errorEvent => {
+    worker.onmessageerror = () => {
       gActiveWorkers.delete(worker);
       worker.terminate();
-      if (errorEvent instanceof ErrorEvent) {
-        const { message, filename, lineno } = errorEvent;
-        const error = new Error(`${message} at ${filename}:${lineno}`);
-        error.name = "WorkerMessageError";
-        reject(error);
-      } else {
-        reject(new Error("Error in worker"));
-      }
+      reject(new Error("Error in worker"));
     };
 
     worker.postMessage(initialMessageToWorker);