Fix warning deduplication in attribute table

[gaearon]

This avoids the need to manually patch React locally because of deduplication hiding warnings.
It takes us further from #10587 but I think that:

• We don't want to run headless Chrome as part of every test run anyway
• We can still add a "Save" button and a script that runs yarn start and presses it if we want to

But at least the data generated by this is more accurate than the current version.

[bvaughn]

After pulling this branch, the attr test harness totally crushes my Chrome. So bad that I can't even use Chrome's Task Manager to kill tabs. None of my other tabs (eg Messenger) accept text input, etc.

[bvaughn]

It actually hung so badly I restarted my computer initially. Then as soon as I tried re-opening Chrome- (because of the service workers)- it auto-started and did the same thing. Took me a few minutes of trying to close the tab before it finally closed, then everything was back to normal

[gaearon]

Weird, it works consistently for me. Note it’s supposed to take about a minute — you can see the progress in Chrome title bar.

[bvaughn]

Yeah, I know. The tab titles were about the only thing that updated during the time, although much slower than what your screenshot is showing.

[gaearon]

What laptop are you using?

[bvaughn]

Work laptop (MacBook Pro, 2.8 GHz i7, 16GB ram).

[gaearon]

Are you on power?