Method constructor

packages/firebase-firestore/index.android.ts:1512–1522

(app?: FirebaseApp)

	_app: FirebaseApp;

	constructor(app?: FirebaseApp) {
		if (app) {
			this._native = com.google.firebase.firestore.FirebaseFirestore.getInstance(app.native);
		} else {
			if (defaultFirestore) {
				return defaultFirestore;
			}
			defaultFirestore = this;
			this._native = com.google.firebase.firestore.FirebaseFirestore.getInstance();
		}
	}

	useEmulator(host: string, port: number) {
		this.native.useEmulator(host === 'localhost' || host === '127.0.0.1' ? '10.0.2.2' : host, port);