WebXR Layers update WebIDL
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Updates the WebXR Layers WebIDL. Implements the "update the pending layers state" algorithm from the layer spec.
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Layout 2020: Implement basic white-space: pre support
With these changes `<pre>` and `<br>` preserve spaces and force line breaks appropriately.
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#26440
- [x] There are tests for these changes
Return Option for Window's layout channel
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`Window::layout_chan()` now returns an `Option<Sender<Msg>>`, returning `None` if the window is dead.
FIX#26969FIX#26429FIX#21208FIX#19092FIX#22559FIX#22584FIX#22652
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- [X] These changes fix#23053
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This is my first contribution, I'm trying to figure things out!
This fix passes the test case shown in #23053, however I don't know what the behavior should be in `Document` and `ScriptThread` if `Window::is_alive()` is false : simply ignore it, don't do anything ? Or is this something that should not happen now that we return false in `Window::force_reflow()` ?
I'm not sure about the directory where the test case should go, any advice?
