Exploratory fix for non-deterministic processing of mixed contours and paths #2977

Job	Run time
Clippy lints	1m 39s
Clippy lints	1m 37s
Rustfmt	1m 12s
Rustfmt	1m 11s
fontbe tests	59s
fontbe tests	57s
fontc tests	1m 13s
fontc tests	1m 33s
Build GS and check the result	1m 41s
Build GS and check the result	3m 17s
cargo check no std	1m 37s
cargo check no std	1m 35s
resources/scripts/ots_test.sh	1m 10s
resources/scripts/ots_test.sh	1m 12s
cargo test fea-rs	1m 6s
cargo test fea-rs	1m 5s
tests other than fontbe,fontc	1s
tests other than fontbe,fontc	2m 18s
	25m 23s

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