Fix cancel button in WebDAV verification

chrome/content/zotero/preferences/preferences.js

@@ -375,6 +375,10 @@ function verifyStorageServer() {
 	var onDone = false;
 	
 	Zotero.Sync.Storage.WebDAV.checkServer()
+	// Get the XMLHttpRequest for possible cancelling
+	.progress(function (obj) {
+		request = obj.xmlhttp;
+	})
 	.finally(function () {
 		verifyButton.hidden = false;
 		abortButton.hidden = true;
@@ -426,9 +430,6 @@ function verifyStorageServer() {
 			}
 		}
 	})
-	.progress(function (obj) {
-		request = obj.request;
-	})
 	.catch(function (e) {
 		Zotero.debug("WebDAV verification failed");
 		Zotero.debug(e, 1);

chrome/content/zotero/xpcom/storage/webdav.js

@@ -1290,11 +1290,12 @@ Zotero.Sync.Storage.WebDAV = (function () {
 			return deferred.resolve([uri, Zotero.Sync.Storage.ERROR_OFFLINE]);
 		}
 		
-		// Pass request to progress handler
-		var obj = {};
-		obj.request = request;
-		deferred.notify(obj)
-		
+		// Pass XMLHttpRequest to progress handler
+		setTimeout(function () {
+			var obj = {};
+			obj.xmlhttp = request;
+			deferred.notify(obj)
+		}, 0);
 		
 		return deferred.promise;
 	};