Adding left over tests using DRY coding
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- [x] These changes add the tests using DRY technique to reduce redundant code for https://github.com/servo/servo/pull/19963
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style: Move most of allowed_in to NonCustomPropertyId.
Also simplify the servo property id to gecko property id conversion to be faster
and less repetitive.
This is in preparation of some patches to properly allow disabled longhands on enabled shorthands, something that we don't contemplate right now.
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Use cstr macro for ffi literal strings
Use `cstr!()` macro with `CStr` to ensure that literal strings used with FFI is properly nul-terminated to avoid cases like #19915.
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Output unquoted family name as a series of identifiers
It tries to serialize unquoted family names as a series of identifiers. For family names which contain special white spaces like leading white space, trailing white space, and consective white spaces, unquoted names are marked quoted in parsing to avoid complicating serialization code.
This fixes [bug 1434802](https://bugzilla.mozilla.org/show_bug.cgi?id=1434802).
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It tries to serialize unquoted family names as a series of identifiers.
For family names which contain special white spaces like leading white
space, trailing white space, and consective white spaces, unquoted names
are marked quoted in parsing to avoid complicating serialization code.
Correct default SelectionStart and SelectionEnd
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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] Added unit tests and wpt for these changes
- [x] These changes fix#19958
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