InputWidget: Focus checkboxes and radios, too, when the label is clicked
InputWidget: Focus checkboxes and radios, too, when the label is clicked

Browsers consistently do this, we were preventing it. This fixes the
behavior of CheckboxInputWidget and RadioInputWidget when the label is
clicked.

Change-Id: I7e4f35f5e8b1d336b34ca2ae3d7f86cfadb3620c
wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui