fix(actionsheet): Use transition instead of animation for backdrop, fix for Android 2.3

Author: Adam Bradley

Diff for: scss/_action-sheet.scss

@@ -4,6 +4,7 @@
  */
 
 .action-sheet-backdrop {
+  @include transition(background-color 300ms ease-in-out);
   position: fixed;
   top: 0;
   left: 0;
@@ -13,13 +14,6 @@
   background-color: rgba(0,0,0,0);
 
   &.active {
-    @include animation(fadeInHalf 0.3s);
-    @include animation-fill-mode(both);
-  }
-
-  &.active-remove {
-    @include animation(fadeOutHalf 0.3s);
-    @include animation-fill-mode(both);
     background-color: rgba(0,0,0,0.5);
   }
 }