src/vs/workbench/api/common/extHostTask.ts/ExtHostTaskBase/terminateTask
class ExtHostTaskBase:	public terminateTask(execution: vscode.TaskExecution): Promise<void> {
		if (!(execution instanceof TaskExecutionImpl)) {
			throw new Error('No valid task execution provided');
		}
		return this._proxy.$terminateTask((execution as TaskExecutionImpl)._id);
	}