* [ASTextNode] Reset _composedTruncationText when attributedText is updated
Current issue:
1) Set `attributedText` in `ASTextNode` with whiteColor
2) `_composedTruncationText` gets updated to take on this new color attribute
3) Set the `attributedText` with greenColor
4) The `_composedTruncationText` gets updated with the new attributes, but does NOT overwrite any existing attributes — i.e., does not overwrite the white color with green. Comment from `_locked_prepareTruncationStringForDrawing:`:
`
// Add any of the original string's attributes to the truncation string,
// but don't overwrite any of the truncation string's attributes
`
* michael’s suggestion
* Improve locking situation in ASDisplayNode subclasses
* Adress first number of comments
* Don’t hold the lock while calling _updateComposedTruncationText
