Pin collection cellNode.frame = contentView.bounds (#2884)

AsyncDisplayKit/ASCollectionView.mm

@@ -121,6 +121,15 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
   self.layoutAttributes = layoutAttributes;
 }
 
+/**
+ * Keep our node filling our content view.
+ */
+- (void)layoutSubviews
+{
+  [super layoutSubviews];
+  self.node.frame = self.contentView.bounds;
+}
+
 @end
 
 #pragma mark -