[fixed] don't access ReactDOM.createPortal if DOM not available

[keeganstreet]

Fixes #824

Changes proposed:

• Access ReactDOM.createPortal via a function instead of directly, so it is only accessed when required, not when the script is compiled. Stops errors being thrown when bundled into script that is run in an environment without access to ReactDOM.

Upgrade Path (for changed or removed APIs):

N/A

Acceptance Checklist:

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

[coveralls]

Coverage remained the same at 82.632% when pulling 024b640 on keeganstreet:lazy-access-of-react-dom-createportal into 421a1c8 on reactjs:master.

[diasbruno]

Maybe something like this will work: const isReact16 = canUseDOM && ReactDOM.createPortal !== undefined;.
If we don't have browser-like env, we don't render the modal anyways...

What do you think?

[keeganstreet]

@diasbruno sounds good, that would require fewer changes. I have just tested that and it will resolve the problem for us. I'll push an update to this branch.

[diasbruno]

Thanks, @keeganstreet!!

[diasbruno]

I've updated the title so it's easy to find.

[keeganstreet]

Not a problem @diasbruno :-) Thanks for your help!

Do you have a release schedule for npm? Wondering when we'll be able to have this fix for our system or if we need to put in a temporary workaround?