Add WebGL conformance 2.0.0 tests
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This PR includes WebGL conformance 2.0.0 tests. For now I have disabled three folders in the new suite:
- `Conformance`: Tests WebGL 1.0 API like the current 1.0.3 suite we are using, but it includes a lot more tests and many expectations have to be updated. This is better to do in a separate PR because it will require to update github intermittent paths again and maybe detect new intermittents.
- `Conformance2\textures`: It causes a lot of timeouts because of using videos, svgs, and other complicated formats.
- `deqp`: It's a extra GPU testing suite included in the Khronos 2.0.0 suite. Disabled for now because it causes some timeouts.
So in a nutshell, it uses part of the 2.0.0 suite to test webgl 2.0 and keeps using 1.0.3 in order to test WebGL 1.0. It's good enough to enable TDD for the new WebGL 2.0 features
We can create follow-up issues for the next steps:
* deprecate 1.0.3 and use the new 'conformance' folder in 2.0.0 in order to test WebGL 1.0
* Enable `conformance2/textures` and 'deqp' tests once WebGL 2.0 implementation is more advanced or the timeouts are monitored in more detail.
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This enables it to be compiled without libservo:
```
cargo build --manifest-path components/script/Cargo.toml
```
… and then to be added to http://perf.rust-lang.org/
Mention that we need Python3 to build on CentOS
Mention that we need Python3 to build on CentOS
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Avoid decoding XHR type="json" responses as UTF-16BE/LE
https://infra.spec.whatwg.org/#parse-json-from-bytes says to use
"UTF-8 decode" rather than "decode", so UTF-16BE/LE BOM should
not be honored.
CC @SimonSapin
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