Remove support for energy and heartbeats profiling
Both are disabled by default (energy at compile-time, heartbeats with a run-time option). Neither is tested of CI. Neither has been used in a long time. They might have Undefined Behavior: https://github.com/servo/servo/issues/26550#issuecomment-634238098. They each depend on a mostly-unmaintained C library. The thread-safety expectation of those libraries are unknown.
Add VTTRegion and part of VTTCue DOM interfaces
<!-- Please describe your changes on the following line: -->
Hello! In this PR I implemented the VTTRegion DOM interface and part of VTTCue (#22312). Before continuing I thought it's maybe a good idea to first request a review or even merge what I did up to this point, as I might get stuck on the next part. I have a slight idea of what needs to be done (I assume it's hooking the GStreamer parser somewhere in `GetCueAsHTML()`), but a short outline or some more instructions would help a lot.
I updated test expectations by first running:
```
./mach test-wpt tests/wpt/web-platform-tests/webvtt/api --log-raw servo.log --pref dom.webvtt.enabled=true
```
then
```
./mach update-wpt servo.log
```
Thanks!
---
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- [ ] These changes fix #___ (GitHub issue number if applicable)
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The angle and disable-vsync options were declared as global options but
only used in the Glutin embedding for desktop builds. Moving them to
the Glutin embedding code makes them easier to update.
Partially fixes#23009
There are a few canvas2d-related dependencies that haven't updated, but they
only use euclid internally so that's not blocking landing the rest of the
changes.
Given the size of this patch, I think it's useful to get this landed as-is.
