Don't invalidateCalculatedLayout when ASTextCellNode's text is changed

Because calling -invalidateCalculatedLayout removes the current constrained size and therefore any -setNeedsLayout calls in the future won't have a valid constrained size to proceed.

Instead, cell nodes should be relaid-out using the new APIs introduced in ASTableView and ASCollectionView, which are -relayoutRowAtIndexPath:withRowAnimation and -relayoutItemAtIndexPath, respectively.

AsyncDisplayKit/ASCellNode.m

@@ -123,7 +123,6 @@ static const CGFloat kFontSize = 18.0f;
   _textNode.attributedString = [[NSAttributedString alloc] initWithString:_text
                                                                attributes:@{NSFontAttributeName: [UIFont systemFontOfSize:kFontSize]}];
 
-  [self invalidateCalculatedLayout];
 }
 
 @end