Update detectElementResize to support rendering into iframes and child windows

[ahutchings]

Without these changes, the size of elements rendered in remote windows is incorrectly detected as height 0/width 0.

• Create detectElementResize CSS in the document containing the rendered AutoSizer.
• Create the resize trigger element using the document containing the rendered AutoSizer.

I'm not sure how to go about testing for this change - any suggestions are welcome.

[bvaughn]

Can you point me at an example of the type of thing you're trying to do that this change enables? A Codesandbox demo would be great!

[ahutchings]

Sure, I created a Codesandbox here: https://codesandbox.io/s/nro7yzrqv0.

Two popup windows are opened -

• The one with the red square is using the unpatched version of react-virtualized, so the detectElementResize CSS is not appended to its document tag, and so the square does not resize.
• The one with the green square is using the changes in this PR, which append the detectElementResize CSS to the owning document of the AutoSizer's parent node.

I also updated the PR to remove some changes to AutoSizer that turned out to be unnecessary.

[bvaughn]

Both pop-up windows appear to resize the same for me. (Although neither shows the background color correctly. I have to inspect the HTML manually and watch it being updated.)

[ahutchings]

Oops, turns out some of those changes are needed for Chrome, but not for Firefox. Working on adding them back now.

[ahutchings]

Pushed a new commit and updated the Codesandbox. It now works properly in both Chrome and Firefox.

[bvaughn]

Thank you for updating the CodeSandbox. Sorry it has taken me so long to circle back here. I've been busy. 😄

I think this looks okay, although I haven't messed around with portals in popup windows before so I don't have any direct experience.

I've tested your change locally and verified that it doesn't seem to cause any regressions. So let's roll with it. 👍

[TrySound]

@bvaughn Is it possible to cover it with puppeteer tests?

[bvaughn]

I dunno. Maybe?

[TrySound]

@ahutchings Would you like to take care about test for this case?

[ahutchings]

Sure, I will take a look at creating a test case for this. Looks like I can use the WindowScroller end-to-end test as an example.

[bvaughn]

Nice! Thanks!