fix pagerNode to automatically scale to bounds size when rotated (facebookarchive#2933)

Author: Hannah Troisi

examples/VerticalWithinHorizontalScrolling/Sample/ViewController.m

@@ -77,11 +77,15 @@ - (ASCellNode *)pagerNode:(ASPagerNode *)pagerNode nodeAtIndex:(NSInteger)index
   CGSize boundsSize = pagerNode.bounds.size;
   CGSize gradientRowSize = CGSizeMake(boundsSize.width, 100);
   GradientTableNode *node = [[GradientTableNode alloc] initWithElementSize:gradientRowSize];
-  node.style.preferredSize = boundsSize;
   node.pageNumber = index;
   return node;
 }
 
+- (ASSizeRange)pagerNode:(ASPagerNode *)pagerNode constrainedSizeForNodeAtIndex:(NSInteger)index;
+{
+  return ASSizeRangeMake(pagerNode.bounds.size);
+}
+
 - (NSInteger)numberOfPagesInPagerNode:(ASPagerNode *)pagerNode
 {
   return 10;