Added a small-res fix to ToggleSwitch's position.

It corrects a rounding and conversion issue on the line-height property that causes the position of the font-symbol inside the element to not remain centered. Webkit appears to be lazily rounding to the wrong pixel in some cases which causes this offset.

Enyo-DCO-1.1-Signed-off-by: Blake Stephens <blake.stephens@lge.com>