collectionView.contentSize.height is always 0, fix bei using ollectio…

[officebluesource]

…nView.collectionViewLayout.collectionViewContentSize.height

Changes in this pull request

Issue fixed: https://github.com/Instagram/IGListKit/issues/1250

Checklist

• [x ] All tests pass. Demo project builds and runs.
• [ ] I added tests, an experiment, or detailed why my change isn't tested.
• [ ] I added an entry to the CHANGELOG.md for any breaking changes, enhancements, or bug fixes.
• [ ] I have reviewed the contributing guide

[facebook-github-bot]

Thank you for your pull request and welcome to our community. We require contributors to sign our Contributor License Agreement, and we don't seem to have you on file. In order for us to review and merge your code, please sign up at https://code.facebook.com/cla. If you are contributing on behalf of someone else (eg your employer), the individual CLA may not be sufficient and your employer may need the corporate CLA signed.

If you have received this in error or have any questions, please contact us at [email protected]. Thanks!

[iglistkit-bot]

	1 Warning
:warning:	All pull requests should have a milestone attached, unless marked #trivial.

Generated by :no_entry_sign: Danger

[rnystrom]

@bluesource can you add a failing unit test that this change passes?

_{Sent with GitHawk}

[TimOliver]

Since the author never got back to us, I think it's fine to close this now.

@bluesource If you think this PR is still relevant, feel free to re-open. Thanks!