Drop isSupported injection, bump rxfire #2124

Job	Run time
Build	47s
Contribute Node 20 (ubuntu-latest)	1m 30s
Contribute Node 20 (macos-latest)	2m 6s
Contribute Node 20 (windows-latest)	3m 41s
Test chrome-headless	1m 14s
Test Node 18 (ubuntu-latest)	17s
Test firefox-headless	1m 8s
Test Node 20 (ubuntu-latest)	32s
Test Node 22 (ubuntu-latest)	20s
Test Node 18 (macos-latest)	36s
Test Node 20 (macos-latest)	32s
Test Node 22 (macos-latest)	35s
Test Node 18 (windows-latest)	53s
Test Node 20 (windows-latest)	1m 8s
Test Node 22 (windows-latest)	1m 21s
Publish (NPM)	0s
Branch protection	1s
	16m 41s

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