src/vs/workbench/api/common/extHostCommands.ts/ExtHostCommands/$getContributedCommandHandlerDescriptions
class ExtHostCommands:	$getContributedCommandHandlerDescriptions(): Promise<{ [id: string]: string | ICommandHandlerDescription }> {
		const result: { [id: string]: string | ICommandHandlerDescription } = Object.create(null);
		for (let [id, command] of this._commands) {
			let { description } = command;
			if (description) {
				result[id] = description;
			}
		}
		return Promise.resolve(result);
	}