Bug 865061: tests/test-window-utils.test window watcher without untracker was timing out, either because of the needless extra logic here or because of the setTimeout

Also this test wasn't waiting for the window it opened to finish closing before completing
Merge pull request #969 from erikvold/865061

Fix Bug 865061: tests/test-window-utils.test window watcher without untracker fix r=Mossop