style: Make the whole style crate independent of the implementation
This allows, among other things, having different implementations for parsing pseudo{elements, classes} in both `ports/geckolib` and in servo.
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This is unfortunate, but making that useful would require parameterizing
`SharedLayoutContext` and `LayoutContext` depending on the
`SelectorImpl` (which is a **huge** work right now).
Probably the easier way to do it, and probably the one that keeps the
layout code more legible, and since there won't be multiple
implementations at the same compilation unit, would be "defining" a
default implementation for layout via feature flags.
That should allow us to remove the components/style/servo.rs file.
This commit refactors the style crate to be completely independent of
the actual implementation and pseudo-elements supported.
This also adds a gecko backend which introduces parsing for the
anonymous box pseudo-elements[1], although there's still no way of
querying them.
https://mxr.mozilla.org/mozilla-central/source/layout/style/nsCSSAnonBoxList.h
Download extra stdlib only when required: #9557
Split [`ensure_bootstrap`](https://github.com/danlrobertson/servo/blob/i9557/python/servo/command_base.py#L397-L422) into two phases including a phase checking the compiler, and a phase checking for target libraries. E.g.
```
# should download the stdlib for "i686-unknown-linux-gnu", "arm-linux-androideabi"
# and the hosts target
./mach build -d --target i686-unknown-linux-gnu --android
# should only download the stdlib for the hosts target
./mach build -d
```
Let me know if I missed anything! There are a few parts of this patch in its current state that I'm not a huge fan of, but I couldn't think of a better way in the moment.
Still new to working on servo, so any comments or critiques are welcome!
Fix#9557
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Calculate correct mp4 header length.
The calculation of MP4 frame length is incorrect, shifting values by 1 bit instead of 8 bits. It works for the test MP4 file because the length of the frame is less than 256 bytes, so the shifted values are all zero.
This PR changes the code to calculate the length correctly. It adds a test to check a fake long stream. Still not long enough to test completely, but at least detects the problem with the original code.
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Add a "mach test-wpt --chaos" mode for reproducing intermittent failures using rr
This adds a new `--chaos` flag to the `test-wpt` and `test-css` commands. This will run a test repeatedly until it fails, recording it with the rr debugger in chaos mode. Requires a recent master build of rr.
```
./mach test-wpt --chaos test.html
```
is shorthand for:
```
./mach test-wpt --repeat-until-unexpected \
--debugger rr \
--debugger-args "record --chaos" \
--include test.html
```
This PR currently includes changes to wptrunner which were also submitted upstream as w3c/wptrunner#170. We should not merge this until that upstream PR is merged. CC @jgraham
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