BHV-16137: Only set rtl property when there is content.

### Issue
The `rtl` property of a control is being incorrectly set when there is no content. We had made a previous fix for this with respect to the `direction` style property, but had missed including the `rtl` property in the conditional.

### Fix
We only set the `rtl` property if we have content from which to determine directionality.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>