[fixed] Cancel requested animation frame on unmount.

[adriantrunzo]

Fixes #882 .

Changes proposed:

• Be sure to cancel the animation frame that is requested in the ModalPortal open method so that a state change is not potentially requested after the component is unmounted.

In the issue description I mentioned that isMounted might be a potential fix, but then I read that it is an antipattern. The componentWillUnmount method is already clearing a timeout, so canceling the animation seems like the best option.

I can confirm that these changes fix the error message I was seeing in the jest/testing-library environment I am using in a separate project. It is unclear to me how to reproduce this race condition in the testing setup used in this project. Any ideas would be appreciated.

Acceptance Checklist:

• The commit message follows the guidelines in CONTRIBUTING.md.
• Documentation (README.md) and examples have been updated as needed.
• If this is a code change, a spec testing the functionality has been added.
• If the commit message has [changed] or [removed], there is an upgrade path above.

[coveralls]

Coverage decreased (-0.2%) to 84.474% when pulling ba8b6c2 on adriantrunzo:master into fc76b0c on reactjs:master.

[diasbruno]

Good catch! Thanks.

[mbclu]

Is it possible to get this released? The project I'm working on is trying to pull in react-modal but finding that our test suite is leaving some warnings sprinkled about that I suspect this might resolve.

Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method.
        in ModalPortal (created by Modal)
        in Modal (created by Modal)
        in Modal (created by ConfirmationModal)
        in ConfirmationModal (created by View)
        in View (created by LoadingContent)
        in div (created by LoadingContent)

[diasbruno]

Released version 3.14.3.