title: Masonry animationWithDuration doesn't animate
body: <p>I am trying to animate a UIWebView in from the bottom on top of my viewController, and I am using masonry (<a href="https://github.com/Masonry/Masonry" rel="nofollow">https://github.com/Masonry/Masonry</a>).</p>
  
  <p>I initially create my webview with the size of 0 - (x,y,height and width), and I then try to animate it so that the webview animates "on top" of the viewcontroller. The webview is shown, but it doesn't animate in place - it just appears immediately. 
  Can anyone who has experience guide me in the right direction? </p>
  
  <p>This is my button action</p>
  
  <pre><code>-(void)didPressBtn{
      self.infoView = [UIWebView new];
      self.infoView.scalesPageToFit = YES;
      self.infoView.backgroundColor = [UIColor whiteColor];
      self.infoView.delegate = self;
      [self.scrollView addSubview:self.infoView];
      [self.infoView makeConstraints:^(MASConstraintMaker *make) {
          make.edges.equalTo(@(0));
      }];
  
  
      [self.scrollView layoutIfNeeded];
      //FIXME: Hmmm it doesn't really animate!?
      [UIView animateWithDuration:1 animations:^{
          [self.scrollView setContentOffset:CGPointMake(0, 0)];
          [self.infoView makeConstraints:^(MASConstraintMaker *make) {
              make.edges.equalTo(self.scrollView);
          }];
  
          [self.scrollView layoutIfNeeded];
  
      } completion:^(BOOL finished) {
                  [self.infoView loadRequest:[[NSURLRequest alloc] initWithURL:[[NSURL alloc] initWithString:NSLocalizedString(@"INFORMATION_URL", )] cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:15]];
      }];
  }
  </code></pre>
  
  <p>My viewDidLoad</p>
  
  <pre><code>- (void)viewDidLoad
  {
      [super viewDidLoad];
  
      self.scrollView = [UIScrollView new];
      self.scrollView.backgroundColor = [UIColor whiteColor];
      [self.view addSubview:self.scrollView];
      [self.scrollView makeConstraints:^(MASConstraintMaker *make) {
          make.edges.equalTo(self.view);
      }];
  
      UIView *contentView = [UIView new];
      [self.scrollView addSubview:contentView];
  
      [contentView makeConstraints:^(MASConstraintMaker *make) {
          make.edges.equalTo(self.scrollView);
          make.width.equalTo(self.scrollView);
      }];
  
  //Then adding buttons and such...
  }
  </code></pre>