Remove get_location_with_offset
Now that rust-cssparser reports 1-based locations, bump the required
cssparser version and remove get_location_with_offset. Previously,
some code paths were not calling get_location_with_offset; see
https://bugzilla.mozilla.org/show_bug.cgi?id=1398869 for some
background.
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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 fix https://bugzilla.mozilla.org/show_bug.cgi?id=1398869 (github issue number if applicable).
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- [ ] There are tests for these changes OR
- [x] These changes do not require tests because tests are in rust-cssparser and/or M-C
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