Drop workaround for the old browser header bar

When the OSK appears, we scroll the focused editable element in to view. We currently have a bit of a hacky workaround in Oxide to prevent this functionality from interacting badly with the browser's header bar (see https://bugs.launchpad.net/oxide/+bug/1301681/comments/3). The workaround basically avoids scrolling during the resize, but instead scrolls once after a short delay when resizing has finished.

It should be possible for us to remove this workaround now that the browser is using LocationBarController. Obviously, we can only do this once the browser on Krillin is using LocationBarController.