[macos] Move TextInputPlugin outside of visible area

[knopp]

TextInputPlugin must be visible and in view hierarchy for emoji picker to work. This is trivial change that moves it completely outside of visible area.

Fixes flutter/flutter#118504

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[knopp]

@Hixie, does this need a test?

[justinmc]

@knopp Thanks for the quick fix here, I really appreciate it! LGTM with a test or a test exemption.

You'll have better luck getting ahold of Hixie on Discord for a test exemption. Or, is it possible to test this? I didn't see anything in the NSTextView docs about getting the frame, but I'm not super familiar with AppKit.

[cbracken]

Thanks for fixing! Please add a test so we don't regress this.

You should be able to create a newly initialised plugin, then check NSIsEmptyRect(plugin.frame.size) in a new test in shell/platform/darwin/macos/framework/Source/FlutterTextInputPluginTest.mm

[knopp]

Thanks for fixing! Please add a test so we don't regress this.

You should be able to create a newly initialised plugin, then check NSIsEmptyRect(plugin.frame.size) in a new test in shell/platform/darwin/macos/framework/Source/FlutterTextInputPluginTest.mm

So, the original comment says that the TextInputPlugin view must not be empty. My linked PR has put the TextInputPlugin to view hierarchy (needed for emoji picker to work), which made it visible.

This PR fixed it by moving it out of visible area, while still keeping the TextInputPlugin not empty.

Hoever I played with this a bit, I made the TextInputPlugin empty (zero size), and everything worked as expected (no visual glitches, IME working as expected, accessibility working too). I think the original non empty size was enforced by @chunhtai in #25600, but it doesn't seem to be necessary?

[knopp]

@chunhtai, any chance you remember why non-empty rect was needed? I tried this with empty rect and everything seems to work just fine (including IME + voiceover). It is possible that the difference before and now is that the plugin is now in view hierarchy (it wasn't originally)/

I'm inclined to go with empty rect since it seems cleaner. Test added.

[cbracken]

@chunhtai is out for couple weeks; should be back in early Feb I believe. If the empty rect works, I agree we should go with that. Was there any info in the commit comment or (since our infra was removing commit comments other than the first line, for a while) linked GitHub PR/Issue?