Add support for files with class properties

[jmonster]

closes #64

[Turbo87]

thanks @jmonster!

can you add a test case for this so that we don't regress on this issue? 🙏

[jmonster]

@Turbo87 I don't mean to neglect this PR but I had a difficult time coming up with a simple way to test this change. Could you offer any guidance for how you imagine this property being tested?

I attempted to simply use the new class syntax in a test but I believe it passed with and without the change from this PR 🤷‍♂

[Turbo87]

I attempted to simply use the new class syntax in a test but I believe it passed with and without the change from this PR

that would have been my idea. seems surprising that it doesn't work. do you have any idea why it works without the change?

[jmonster]

@Turbo87 I updated this PR to have a test, but note as long as the file contains this.intl.t('js-translation'); -- even if I precede it with throw new Error("anything") or return false -- the tests pass. Removing that line, however, yields test failures.

Adding classProperties (the original change in this PR) has no effect on these tests passing/failing

Any advice how to proceed?