Start a JSON-based test framework.
Add tests, fix bugs.
More tests and fixes.
Add a PrecentageToken node, distinct from DimensionToken.

... to tell 12% apart from 12\%.

Also more tests and fixes.
Add "one component value" tests.
Add "one declaration" tests.
Add declaration list tests.
Add rule and stylesheet tests.
Document JSON representation of rules and declarations.
Remove the bad-escape error. Delim('\\') will trigger an error anyway.
Make ';' end all declarations, forbid top-level '!'

… in declaration values, other than for !important
Add some tests from rust-cssparser
Add 'json-tests/' from commit 'b38e27ae219405c5173db2fd9eab365dec14c5bb'

git-subtree-dir: json-tests
git-subtree-mainline: bf730ed16eca5410d81e66a7e595edd6e53dd27a
git-subtree-split: b38e27ae219405c5173db2fd9eab365dec14c5bb
Test with local JSON files, imported with git-subtree.