Revert "[ASCellNode] Fix applyLayoutAttributes not called, add readonly layoutAttributes property (#2321)"

This reverts commit f9ee1dd4b6.

This appears to have caused a test failure:
https://travis-ci.org/facebook/AsyncDisplayKit/jobs/164532435

AsyncDisplayKit/ASCollectionView.mm

@@ -47,15 +47,12 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
 
 @interface _ASCollectionViewCell : UICollectionViewCell
 @property (nonatomic, weak) ASCellNode *node;
-@property (nonatomic, strong) UICollectionViewLayoutAttributes *layoutAttributes;
 @end
 
 @implementation _ASCollectionViewCell
 
 - (void)setNode:(ASCellNode *)node
 {
-  ASDisplayNodeAssertMainThread();
-  node.layoutAttributes = _layoutAttributes;
   _node = node;
   [node __setSelectedFromUIKit:self.selected];
   [node __setHighlightedFromUIKit:self.highlighted];
@@ -75,25 +72,14 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
 
 - (void)prepareForReuse
 {
-  _layoutAttributes = nil;
-  _node.layoutAttributes = nil;
-
   // Need to clear node pointer before UIKit calls setSelected:NO / setHighlighted:NO on its cells
   self.node = nil;
   [super prepareForReuse];
 }
 
-/**
- * In the initial case, this is called by UICollectionView during cell dequeueing, before
- *   we get a chance to assign a node to it, so we must be sure to set these layout attributes
- *   on our node when one is next assigned to us in @c setNode: . Since there may be cases when we _do_ already
- *   have our node assigned e.g. during a layout update for existing cells, we also attempt
- *   to update it now.
- */
 - (void)applyLayoutAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes
 {
-  _layoutAttributes = layoutAttributes;
-  _node.layoutAttributes = layoutAttributes;
+  [_node applyLayoutAttributes:layoutAttributes];
 }
 
 @end