Merge pull request #1276 from googlefonts/skip-zero-value-class-class… #3232

Job	Run time
Rustfmt	1m 8s
cargo check no std	1m 28s
resources/scripts/ots_test.sh	1m 4s
Clippy lints	1m 31s
fontbe tests	55s
fontc tests	1m 12s
Build GS and check the result	3m 9s
cargo check wasm	1m 12s
cargo test fea-rs	1m 1s
tests other than fontbe,fontc	2m 5s
	14m 45s

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