extensions/typescript-language-features/src/task/taskProvider.ts/TscTaskProvider/getWatchTask
class TscTaskProvider:	private getWatchTask(workspaceFolder: vscode.WorkspaceFolder | undefined, label: string, command: string, args: string[], watchTaskidentifier: TypeScriptTaskDefinition) {
		const watchTask = new vscode.Task(
			watchTaskidentifier,
			workspaceFolder || vscode.TaskScope.Workspace,
			vscode.l10n.t("watch - {0}", label),
			'tsc',
			new vscode.ShellExecution(command, [...args, '--watch']),
			'$tsc-watch');
		watchTask.group = vscode.TaskGroup.Build;
		watchTask.isBackground = true;
		return watchTask;
	}