LibWeb: Run the unfocusing steps when a click does not focus anything

For example, when clicking the document body outside of a focused input
element, we should unfocus that element.

Userland/Libraries/LibWeb/Internals/Internals.idl

@@ -10,6 +10,8 @@
     undefined sendText(HTMLElement target, DOMString text);
     undefined commitText();
 
+    undefined click(double x, double y);
+
     boolean dispatchUserActivatedEvent(EventTarget target, Event event);
 
 };