Introduced in I740600d18859422b2f98a5ef92d0321f6e9615a2. We need to prevent the default action (navigating a link) so that our custom code has a chance to run. Before it was synchronous so it called location.href before default action had a chance to execute. When it was made asynchronous, the default action got executed before our custom code. Change-Id: I292f99aa5f5ff536d8197174c317018462685866