[JavaScript] Fix incorrect this.channel access #1034

Job	Run time
build (macos-11, tool)	1m 55s
cpp-lib-build (macos-11, clang, ON)	7m 48s
build (macos-11, cpp)	31m 24s
cpp-lib-build (macos-11, clang, OFF)	8m 29s
build (macos-11, csharp)	9m 54s
cpp-lib-build (macos-11, gcc, ON)	7m 54s
build (macos-11, dart)	5m 45s
cpp-lib-build (macos-11, gcc, OFF)	7m 51s
build (macos-11, go)	4m 46s
cpp-lib-build (ubuntu-20.04, clang, ON)	3m 25s
build (macos-11, java)	2m 2s
cpp-lib-build (ubuntu-20.04, clang, OFF)	3m 18s
build (macos-11, javascript)	2m 41s
cpp-lib-build (ubuntu-20.04, gcc, ON)	3m 0s
build (macos-11, typescript)	18m 28s
cpp-lib-build (ubuntu-20.04, gcc, OFF)	3m 21s
build (macos-11, php)	21s
cpp-lib-build (windows-2022, clang, ON)	4m 10s
build (macos-11, python3)	2m 1s
cpp-lib-build (windows-2022, clang, OFF)	5m 33s
build (ubuntu-20.04, tool)	1m 4s
cpp-lib-build (windows-2022, cl)	4m 15s
build (ubuntu-20.04, cpp)	17m 7s
build (ubuntu-20.04, csharp)	5m 9s
build (ubuntu-20.04, dart)	3m 31s
build (ubuntu-20.04, go)	2m 21s
build (ubuntu-20.04, java)	1m 5s
build (ubuntu-20.04, javascript)	1m 24s
build (ubuntu-20.04, typescript)	9m 45s
build (ubuntu-20.04, php)	1m 43s
build (ubuntu-20.04, python3)	1m 18s
build (windows-2022, tool)	1m 37s
build (windows-2022, cpp)	22m 13s
build (windows-2022, csharp)	7m 24s
build (windows-2022, dart)	4m 17s
build (windows-2022, go)	5m 32s
build (windows-2022, java)	1m 48s
build (windows-2022, javascript)	2m 13s
build (windows-2022, typescript)	23m 57s
build (windows-2022, php)	2m 8s
build (windows-2022, python3)	1m 39s
	4h 15m 36s

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