Bug 1611424 - Intermittent TV dom/broadcastchannel/tests/test_wasm.html, r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D60977

--HG--
extra : moz-landing-system : lando

dom/broadcastchannel/tests/test_wasm.html

@@ -14,7 +14,7 @@ bc.onmessage = e => {
   bc.postMessage(e.data);
   bc.close();
 }
-self.postMessage("ready");
+bc.postMessage("ready");
 </script>
 
 <script type="application/javascript">
@@ -76,20 +76,20 @@ function test_worker() {
     return;
   }
 
-  const blob = new Blob([document.getElementById('myWorker').textContent]);
-  const w = new Worker(URL.createObjectURL(blob));
-  w.onmessage = e => {
-    is(e.data, "ready", "The worker is ready");
-    const bc = new BroadcastChannel('b');
+  const bc = new BroadcastChannel('b');
+  bc.onmessage = e => {
+    if (e.data === "ready") {
+      bc.postMessage({ wasmModule });
+      return;
+    }
 
-    bc.onmessage = ee => {
-      ok(ee.data.wasmModule instanceof WebAssembly.Module, "WasmModule received");
-      bc.close();
-      next();
-    };
-
-    bc.postMessage({ wasmModule });
+    ok(e.data.wasmModule instanceof WebAssembly.Module, "WasmModule received");
+    bc.close();
+    next();
   };
+
+  const blob = new Blob([document.getElementById('myWorker').textContent]);
+  new Worker(URL.createObjectURL(blob));
 }
 
 const tests = [