removed unnecessary type assertion

Feiyang1 · Feiyang1 · commit 9722dbc243d0 · 2019-11-04T14:26:14.000-08:00
diff --git a/packages/firestore/src/api/credentials.ts b/packages/firestore/src/api/credentials.ts
@@ -175,7 +175,7 @@ export class FirebaseCredentialsProvider implements CredentialsProvider {
           this.auth = auth;
           if (this.tokenListener) {
             // tokenListener can be removed by removeChangeListener()
-            this.auth.addAuthTokenListener(this.tokenListener!);
+            this.auth.addAuthTokenListener(this.tokenListener);
           }
         },
         () => {

Original file line number	Diff line number	Diff line change
`@@ -175,7 +175,7 @@ export class FirebaseCredentialsProvider implements CredentialsProvider {`
`175`	`175`	`this.auth = auth;`
`176`	`176`	`if (this.tokenListener) {`
`177`	`177`	`// tokenListener can be removed by removeChangeListener()`
`178`		`- this.auth.addAuthTokenListener(this.tokenListener!);`
	`178`	`+ this.auth.addAuthTokenListener(this.tokenListener);`
`179`	`179`	`}`
`180`	`180`	`},`
`181`	`181`	`() => {`