fix(dialog): higher '.mdc-dialog__action' specificity

[hvolschenk]

Closes #2243

[hvolschenk]

I don't quite get why this test isn't running: https://travis-ci.org/material-components/material-components-web/jobs/381379433

It doesn't have anything to do with the changes I made here. I also don't get a retry option on the build, don't really want to push up something else to retry it. 😕

[patrickrodee]

Thanks for the PR! Always happy to get contributions :) I have a small change I'd like before I'll merge this.

[patrickrodee]

You can safely remove this line and the change will work as intended.

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for all the commit author(s) or Co-authors. If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.
In order to pass this check, please resolve this problem and have the pull request author add another comment and the bot will run again. If the bot doesn't comment, it means it doesn't think anything has changed.

[googlebot]

CLAs look good, thanks!

[hvolschenk]

Man, again: https://travis-ci.org/material-components/material-components-web/jobs/383029803

ERROR [launcher]: Cannot start Chrome

Anything I can do from my side to spur 'ol Travis along?

[kfranqueiro]

Don't worry about the Travis failure; it's presently unavoidable because the unit tests run through Sauce Labs and use keys configured within Travis, which aren't exposed to forks.

[patrickrodee]

LGTM!