Backed out changeset 6b8f0fd1a9f1 (bug 1416446) for failing browser-chrome's browser/base/content/test/permissions/browser_temporary_permissions_expiry.js on Windows 7 debug without e10s r=backout on a CLOSED TREE

toolkit/content/tests/browser/head.js

@@ -143,10 +143,7 @@ class DateTimeTestHelper {
   async openPicker(pageUrl) {
     this.tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, pageUrl);
     await BrowserTestUtils.synthesizeMouseAtCenter("input", {}, gBrowser.selectedBrowser);
-    // If dateTimePopupFrame doesn't exist yet, wait for the binding to be
-    // attached.
-    // FIXME: This has a race condition and we may miss the following events.
-    //        (bug 1423498)
+    // If dateTimePopupFrame doesn't exist yet, wait for the binding to be attached
     if (!this.panel.dateTimePopupFrame) {
       await BrowserTestUtils.waitForEvent(this.panel, "DateTimePickerBindingReady");
     }
@@ -155,19 +152,9 @@ class DateTimeTestHelper {
   }
 
   async waitForPickerReady() {
-    let readyPromise;
-    let loadPromise = new Promise(resolve => {
-      this.frame.addEventListener("load", () => {
-       // Add the PickerReady event listener directly inside the load event
-        // listener to avoid missing the event.
-        readyPromise = BrowserTestUtils.waitForEvent(this.frame.contentDocument, "PickerReady");
-        resolve();
-      }, { capture: true, once: true });
-    });
-
-    await loadPromise;
+    await BrowserTestUtils.waitForEvent(this.frame, "load", true);
     // Wait for picker elements to be ready
-    await readyPromise;
+    await BrowserTestUtils.waitForEvent(this.frame.contentDocument, "PickerReady");
   }
 
   /**