Bug 1497469 - Dispatch the ValueChange event from UrlbarInput. r=mak

Differential Revision: https://phabricator.services.mozilla.com/D8819

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

browser/components/urlbar/UrlbarInput.jsm

@@ -255,6 +255,11 @@ class UrlbarInput {
     this.inputField.value = val;
     this.formatValue();
 
+    // Dispatch ValueChange event for accessibility.
+    let event = this.document.createEvent("Events");
+    event.initEvent("ValueChange", true, true);
+    this.inputField.dispatchEvent(event);
+
     return val;
   }