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.
Update Firefox version in user agent string
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GitHub is again limiting functionality in Servo due to using an outdated Firefox version in the user agent string. Updating this should get rid of the warning.
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Previously, the `tests` feature flag of the `embedder_traits` crate
caused it and every crate recursively depending on it to be built twice.
This feature flag was used to provide a specific set of "resources"
when running tests. Instead, this commits overrides the `main()` function
of the test harness to change resources at runtime before running any test.
This is done by adding a dependency that has `name = "test"` in its
`[lib]` section of `Cargo.toml`. This overrides the crate found by
`extern crate test;` in code generated by `rustc --test`.
