Gracefully recover when ad block prevents Babel from loading

[bvaughn]

I've seen reports that certain ad blockers (eg Fair AdBlocker 1.404) prevent Babel from loading which causes a script error and results in the following:

We could detect this case (eg no Babel) and show an error message about ad blockers specifically, letting users know to whitelist reactjs.org if they want the live code examples to work.

Note that this issue is related to issue #2 and may be impacted by its implementation.

[bvaughn]

Note that this issue was reported by another user but I am unable to reproduce it. Removing Babel entirely (so it isn't loaded) results in the following for me:

I think this is good enough. 😄

[bvaughn]

Eh, maybe we could improve the error message slightly to mention ad blockers if we detect no Babel. I'll re-open and re-purpose for that.

[renanpvaz]

I can reproduce this, perhaps I can send a PR improving the message.

[bvaughn]

Great! This issue is all yours! 😄

I've added an "in-progress" label so that others will know not to start work on the issue. If you change your mind about the issue, no worries! Just let me know so that I can remove the label and free it up for someone else to claim.

Cheers!