We just need to set `align=start` on `#searchBarVisibleGroup`. There are a
couple of things to note about this:
* The images are stretched only when the Quick Suggest checkbox is visible,
which it isn't unless the Quick Suggest pref is enabled
* This is broken even without the Quick Suggest checkbox because the two images
shrink when the window is narrow
Differential Revision: https://phabricator.services.mozilla.com/D110487
f4fe098e2a