Drop isSupported injection, bump rxfire #2125

Job	Run time
Contribute Node 20 (ubuntu-latest)	1m 34s
Build	33s
Contribute Node 20 (macos-latest)	1m 59s
Contribute Node 20 (windows-latest)	4m 10s
Test Node 18 (ubuntu-latest)	20s
Test chrome-headless	1m 6s
Test Node 20 (ubuntu-latest)	37s
Test Node 22 (ubuntu-latest)	19s
Test firefox-headless	1m 14s
Test Node 18 (macos-latest)	36s
Test Node 20 (macos-latest)	43s
Test Node 22 (macos-latest)	45s
Test Node 18 (windows-latest)	53s
Test Node 20 (windows-latest)	59s
Test Node 22 (windows-latest)	1m 8s
Publish (NPM)	0s
Branch protection	1s
	16m 57s

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