Fix bug, caused by fixing issue #264. (#281)

* Fix rounding error.

* Remove unneeded whitespaces.

Author: dstdnk

src/ios/RNCSliderManager.m

@@ -84,13 +84,15 @@ static float discreteValue(RNCSlider *sender, float value) {
 
     // Round up when increase, round down when decrease.
     double (^_round)(double) = ^(double x) {
-      if (sender.lastValue > value) {
+      if (!UIAccessibilityIsVoiceOverRunning()) {
+        return round(x);
+      } else if (sender.lastValue > value) {
         return floor(x);
       } else {
         return ceil(x);
       }
     };
-  
+
     return
       MAX(sender.minimumValue,
         MIN(sender.maximumValue,