syscall: Revert "release a js.Func object in fsCall"
syscall: Revert "release a js.Func object in fsCall"

This reverts CL 217417 (commit 753d56d3642eb83848aa39e65982a9fc77e722d7).

This change was unintentionally submitted to master during the
Go 1.14 code freeze; it should be sent again for Go 1.15.

Change-Id: Ie790342f227ae3adfc5f9a90ce3abdc2c9be619b
Reviewed-on: https://go-review.googlesource.com/c/go/+/217721
Run-TryBot: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Reviewed-by: Carlos Amedee <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@golang.org>

golang/go,akutz/go,nawawi/go,CAFxX/go,CAFxX/go,CAFxX/go,cloudflare/go,CAFxX/go,akutz/go,nawawi/go,CAFxX/go,nawawi/go,akutz/go,nawawi/go,golang/go,nawawi/go,akutz/go,akutz/go,akutz/go,CAFxX/go,cloudflare/go,nawawi/go,akutz/go,cloudflare/go,nawawi/go,golang/go,CAFxX/go,cloudflare/go,cloudflare/go,golang/go,nawawi/go,CAFxX/go,akutz/go,cloudflare/go,cloudflare/go,golang/go,golang/go,golang/go,cloudflare/go,golang/go