Phantom types: fix wordbreak

[BrianHicks]

wordBreak currently has the wrong signature in phantom-types 😢 This fixes it. I think it's right! But always good to have a second set of eyes on it 😄

Also adds a Travis check for type signatures so future issues on phantom-types should fail the build.

[brianvanburken]

As far as I can see word-break is not a value but a property so it shouldn't have provides. Source: https://developer.mozilla.org/en-US/docs/Web/CSS/word-break. I see that I did forget to add -> Style in #417. I apologize for the mistake! :(

[BrianHicks]

1. yep! I missed that in another branch too. Awhoops! Once the test suite works again it will catch these. Thanks for the catch. <3
2. you're fine, these things happen. Just needed a little tweak, and I've added a check for that to CI. Thanks for writing it in the first place!

[rtfeldman]

Looks good, thanks @BrianHicks!

And yeah, totally don't sweat it @brianvanburken 😄 - thanks for the contribution!