Implement beforeunload event and infrastructure
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Implementation of:
1. https://html.spec.whatwg.org/multipage/#prompt-to-unload-a-document, and
2. https://html.spec.whatwg.org/multipage/#unload-a-document
---
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- [ ] These changes fix#10787 and fix#20485 and fix#20588 and fix#20496 (github issue number if applicable).
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Remove useless message
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Make session history aware of URLs
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Moved Canvas rendering to a single thread.
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Implements the "Subsequent Steps" part of the [NCSU Canvas rendering project.](https://github.com/servo/servo/wiki/Canvas-rendering-project)
I moved most of the functionality from CanvasPaintThread to CanvasData, so CanvasPaintThread essentially just pulls the info out of the message and calls a method on a particular CanvasData element.
I ran into some awkwardness with the fact that one can only take a single mutable reference from a hashmap, though. DrawImageInOther is not really possible to do with only one reference at a time, so it awkwardly still lives in CanvasPaintThread, basically. I also would've preferred to take the reference at the top as soon as I get the CanvasId, since that looks cleaner than having them all start with "canvas_paint_thread.canvases.get_mut[&canvas_id].unwrap()" but that makes trying to take the second reference for DrawImageInOther fail to compile. I'm definitely open to suggestions on how to make that less gross.
The timed single-canvas drawing improved in performance from around ~2.2ms to around ~1.7ms. Slither.io runs better and doesn't crash, but I'm not having it crash on my copy from before these changes, so I don't know if that's new behavior or not.
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This new implementation of the session history keeps track of
a single tree of browsing contexts and pipelines which represents
the active entry of the session history and it keeps track of
diffs between adjacent entries. This allows use to traverse across
the joint session history by applying diffs to the active tree.
This fixes a regression caused by the glutin update.
We now are creating EGL contexts in Linux Wayland, instead of X context, so the
GLContextFactory assumption of one GL back-end per platform is broken.
This just works around it, for now, but in general I think not relying on
available WebGL state is a good thing, and we do that already for WebVR anyway.
style: Move cursor property out of mako
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Sub-PR of #19015
r? emilio
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Send IPC receiver for canvas as part of CreateCanvasPaintThread message
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I am not sure if @jdm want this.
r? @jdm
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This trades quite a bit of complicated code in Servo for few more
messages and a significant performance improvement. In particular,
WebRender can search the entire display list at once instead of
ping-ponging down the pipeline tree. This allows us to send mouse
events to the correct pipeline immediately.
Make optional the usage of some unstable features
With `--no-default-features --features default-except-unstable`, more crates can now be compiled on stable Rust. This will help integrate them in rustc’s regression testing and compiler performance benchmarking.
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"javascript:" urls: execute in correct global scope
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#### Summary
This pull request makes `javascript:` urls execute in the correct global scope.
#### Example
```html
<script> var x = 4; </script>
<!-- this branch: logs "4" -->
<!-- master: undefined variable error -->
<a href="javascript:console.log(x)">link</a>
```
#### Questions
I'm new to servo and rust, so I'm unsure about these changes. In particular:
* What's the appropriate place to evaluate the js?
* I moved it to `handle_navigate`, but I'm not sure if this will catch all occurrences of `javascript:` urls. I also don't know if this will execute in the correct thread and the correct window.
* What should I do with the result of the js evaluation?
* I just ignored it. The previous behavior displayed it as the content of a new page load.
---
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- generalize the eval_js_url function so it can be called from
multiple places.
- call it in htmliframeelement.
- if the js eval results in a non-string result, then it won't
navigate to a new page, so don't block on the new page loading.
Problem:
After aborting on a 204 or 205 status code, you could no longer
follow links on the page.
Cause:
`constellation.rs` ignores new LoadUrl requests since the aborted
one is in its `pending_changes` list.
Solution:
Send a message to constellation that lets it clean up its
`pending_changes` list.
Make it possible to close a browsing context from the embedder
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