[Mobile] Fix Shift

Shifting occurring during transition
fixed by making transition backface-
visibility hidden during the
transition.

platform/commonUI/general/res/sass/mobile/_mixins.scss

@@ -92,4 +92,5 @@
 @mixin slMenuTransitions {
     @include transition-duration(.35s);
     transition-timing-function: ease;
+    backface-visibility: hidden;
 }