This makes the magnifying glass icon (search.svg) clickable. Clicking focuses the input field next to the icon, which is the expected, helpful behaviour in my opinion. This is especially helpful with the "compact links" beta feature where the input box is completely invisible and the only remaining indicator that the user can type something is the blinking cursor. If the focus is lost for some reason, this patch allows the user to click the magnifying icon and re-focus the input field again.
The border on top is white and therefore not visible. It's simply the wrong element hidden.
The border at the bottom was gray and visible. It looked like a misplaced 2px border.
thiemowmde