Merge branch 'master' into patch-1

Author: jamesdaniels

src/firestore/document/document.spec.ts

@@ -59,7 +59,7 @@ describe('AngularFirestoreDocument', () => {
     await stock.set(FAKE_STOCK_DATA);
     const obs$ = stock.valueChanges();
     obs$.pipe(take(1)).subscribe(async data => {
-      expect(JSON.stringify(data)).toBe(JSON.stringify(FAKE_STOCK_DATA));
+      expect(data).toEqual(FAKE_STOCK_DATA);
       stock.delete().then(done).catch(done.fail);
     });
   });

src/storage/ref.ts

@@ -31,7 +31,7 @@ export function createStorageRef(
       switchMap(() => ref.getDownloadURL()),
       keepUnstableUntilFirst
     ),
-    getMetadata: () => of().pipe(
+    getMetadata: () => of(undefined).pipe(
       observeOn(schedulers.outsideAngular),
       switchMap(() => ref.getMetadata()),
       keepUnstableUntilFirst