Fixes sizeThatFits issue where the size returned was 0 when using an attributedTruncationToken.
Fixes sizeThatFits issue where the size returned was 0 when using an attributedTruncationToken.

Addresses: #621 and #678.

NewAmsterdamLabs/TTTAttributedLabel,TTTAttributedLabel/TTTAttributedLabel,mattt/TTTAttributedLabel