docs: Update sample to use non-default export (#634)

Author: schmidt-sebastian

handwritten/firestore/dev/src/watch.ts

@@ -22,7 +22,7 @@ import {google} from '../protos/firestore_proto_api';
 import {ExponentialBackoff} from './backoff';
 import {DocumentSnapshotBuilder, QueryDocumentSnapshot} from './document';
 import {DocumentChange, DocumentChangeType} from './document-change';
-import Firestore, {DocumentReference, Query} from './index';
+import {DocumentReference, Firestore, Query} from './index';
 import {logger} from './logger';
 import {QualifiedResourcePath} from './path';
 import {Timestamp} from './timestamp';

handwritten/firestore/dev/test/document.ts

@@ -274,7 +274,7 @@ describe('serialize document', () => {
     }).to.throw('Value for argument "latitude" is not a valid number');
 
     expect(() => {
-      new (Firestore as InvalidApiUsage).GeoPoint();
+      new (GeoPoint as InvalidApiUsage)();
     }).to.throw('Value for argument "latitude" is not a valid number');
 
     expect(() => {