Load GST videofilter plugins.
The video playback tries to create a videobalance element and can't find it without this plugin.
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WebGLSender doesn't really implement Serializable
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Add an API which turns a `WebGLSender` into something that is actually serializable.
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- [X] `./mach test-tidy` does not report any errors
- [X] These changes do not require tests because this is fixing a panic
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Add clipboard cut functionality
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This PR adds clipboard cut functionality. #23735
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<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#23735 (GitHub issue number if applicable)
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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because manually testing whether cutting works is enough.
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Support WebAudio on Windows
These changes improve the GStreamer experience on Windows in several ways:
* we package the set of plugins and their dependencies that Servo requires for media support
* we explicitly load those plugins when starting the media engine rather than relying on an existing gstreamer installation
These changes do not affect the experience on non-Windows platforms, but the path is clear to do so in order to fix problems like #23519. With these changes I can successfully hear a tone when loading https://joshmatthews.net/osc.html in both a desktop build and a UWP build.
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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#23631 and fix#23698
- [x] These changes do not require tests because no tests on windows ;_;
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