Change the definition of `tagtype` from `functype` into `deftype` #270

Job	Run time
build-legacy-exceptions-js-api-spec	29s
build-js-api-spec	29s
build-legacy-exceptions-core-spec	2m 0s
build-core-spec	8m 19s
build-spec-versions	7s
build-web-api-spec	24s
build-code-metadata-spec	2m 56s
publish-spec	9s
	14m 53s

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