<!-- Please describe your changes on the following line: -->
Layout viewer now uses local copy of jquery as requested in ticket, so etc/layout_viewer/viewer.html can work without connection to the internet.
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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 #15964(github issue number if applicable).
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- [ ] There are tests for these changes OR
- [x] These changes do not require tests because changes are tested manually by unplugging the internet connection.
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Source-Repo: https://github.com/servo/servo
Source-Revision: 99f5edbefb69019db0b80688da286a857fd9d6ea
1d737ba29d