[ios] Remove animation of manual fallback cell buttons

Change-Id: Ic5e843b077e36e54e9ce107d865084c8bf6f4258
Reviewed-on: https://chromium-review.googlesource.com/c/1350612Reviewed-by: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Commit-Queue: David Jean <djean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610819}

ios/chrome/browser/ui/autofill/manual_fill/manual_fill_cell_button.mm

@@ -14,15 +14,8 @@
 
 - (void)setHighlighted:(BOOL)highlighted {
   [super setHighlighted:highlighted];
-  auto animations = ^{
-    CGFloat alpha = highlighted ? 0.07 : 0;
-    self.backgroundColor = [UIColor colorWithWhite:0 alpha:alpha];
-  };
-  [UIView animateWithDuration:0.1
-                        delay:0
-                      options:UIViewAnimationOptionBeginFromCurrentState
-                   animations:animations
-                   completion:nil];
+  CGFloat alpha = highlighted ? 0.07 : 0;
+  self.backgroundColor = [UIColor colorWithWhite:0 alpha:alpha];
 }
 
 @end