Remove nonfunctional $icon/$indicator code from OptionWidget

IconElement and IndicatorElement are mixed into DecoratedOptionWidget,
not OptionWidget, so this.$icon and this.$indicator don't exist
yet when this code runs, which means we're just doing
this.$element.prepend( undefined ).append( undefined );

Change-Id: Ib980dad89593638bae10dee6c807694b5e0d5732
Merge "Remove nonfunctional $icon/$indicator code from OptionWidget"