BridgeJS: Move optional JSObject to stack ABI, enabling Optional<@JSC… #2620

Job	Run time
Build for native target (macos-15, Xcode_16.4)	3m 20s
prettier	8s
Test BridgeJS against Swift versions (swift:6.2, 602.0.0)	3m 15s
format	31s
Test BridgeJS against Swift versions (swift:6.1.2, 601.0.0)	3m 3s
check-bridgejs-generated	2m 58s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	16m 23s
Build and Test (ubuntu-24.04, https://download.swift.org/swift-6.3-branch/ubuntu2404/swift-6.3-DE...	13m 24s
Build and Test (ubuntu-24.04, https://download.swift.org/development/ubuntu2404/swift-DEVELOPMENT...	13m 17s
build-examples	20m 38s
Test BridgeJS against Swift versions (swift:6.3, 603.0.0)	3m 3s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.1-release/ubuntu2204/swift-6.1-R...	13m 9s
deploy-examples	8s
	1h 33m 17s

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