title: UIView animateWithDuration jumps to final transform without animation
body: <p>I have the following code to create flip transition. The <code>fromView</code> does not animate the transform and jumps to the final value but the <code>toView</code> correctly animates transform. What could be wrong here?</p>
  
  <pre><code>  toView.hidden = NO;
    toView.transform = CGAffineTransformMake(0, 0, 0, 1, 0, 0);
    [UIView animateWithDuration:0.4
                     animations:^{
                       fromView.transform = CGAffineTransformMake(0, 0, 0, 1, 0, 0);
                     }
                     completion:^(BOOL finished) {
                       fromView.hidden = YES;
                       fromView.transform = CGAffineTransformIdentity;
                       [UIView animateWithDuration:0.4
                                        animations:^{
                                          toView.transform = CGAffineTransformMake(1, 0, 0, 1, 0, 0);
                                        }
                                        completion:nil];
                     }];
  </code></pre>