servo: Merge #19086 - style: Move font-weight outside of mako (from...

servo: Merge #19086 - style: Move font-weight outside of mako (from cbrewster:font_weight_nomako); r=emilio

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes are apart of #19015 (github issue number if applicable).

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- [ ] There are tests for these changes OR
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Source-Repo: https://github.com/servo/servo
Source-Revision: 1e0fd7da3050208621dd08044bb202570638fb3e

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 11e30e17839a10dbfda8f88055392c025652c722