Buggy behavior when the weight or line spacing of text layer inside a padded symbol is edited
**Bug report**

#### Expected behavior:
If I have created a symbol that contains a text layer above a background layer with padding values applied, I expect that if I go back and edit the style of the text, it will not break the padding behaviors for that symbol.

#### Actual behavior:
Changing the text style/weight/size breaks the padding within the symbol in unexpected ways. Text variables get truncated or padding is incorrect.

#### Steps to reproduce:
1. Create a simple symbol in Sketch with a background container and text.
2. Use the symbol, modifying the text, to make sure the padding holds true and the container changes dimensions with the length of the text.
3. Double click to get back to the symbol.
4. Edit the text by changing the font weight.
5. "Return to instance" to see if the symbol is still rendered correctly with the text style change applied.


