Bug 1056017 - [Flatfish][Arabic] Display problem in Settings App - RTL Support Required.

We can keep this `-moz-margin-start: 0` and add one more style at `marker1` (Please check my comments, I left one comment called marker1)

```css
html[dir="rtl"] section[role="region"] ul li > label input[type='range'] {
    left: 0;
    right: 50%;
    -moz-margin-start: 0; /* add this one more style */
}
```