<!-- Please describe your changes on the following line: -->
---
<!-- 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
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r? @bholley
Source-Repo: https://github.com/servo/servo
Source-Revision: 1b2450339c40dbcb65e94a346ea434d45f0edf90