Minimal fix for b/74357976 (#890)

Fixes b/74357976 which caused unauthenticated users to be unable to reach the Firestore backend and updates the changelog.

Author: mikelehen

Firestore/CHANGELOG.md

@@ -1,5 +1,12 @@
 # Unreleased
 
+# v0.10.3
+- [fixed] Fixed a regression in the 4.10.0 Firebase iOS SDK release that
+  prevented the SDK from communicating with the backend before successfully
+  authenticating via Firebase Authentication or after unauthenticating and
+  re-authenticating. Reads and writes would silently be executed locally
+  but not sent to the backend.
+
 # v0.10.2
 - [changed] When you delete a FirebaseApp, the associated Firestore instances
   are now also deleted (#683).

Firestore/Source/Remote/FSTDatastore.mm

@@ -313,7 +313,7 @@ - (void)invokeRPCWithFactory:(GRPCProtoCall * (^)(void))rpcFactory
                         [FSTDatastore
                             prepareHeadersForRPC:rpc
                                       databaseID:&self.databaseInfo->database_id()
-                                           token:(result.is_valid() ? result.token()
+                                           token:(result.user().is_authenticated() ? result.token()
                                                                     : absl::string_view())];
                         [rpc start];
                       }

Firestore/Source/Remote/FSTStream.mm

@@ -297,7 +297,7 @@ - (void)resumeStartWithToken:(const Token &)token error:(NSError *)error {
 
   [FSTDatastore prepareHeadersForRPC:_rpc
                           databaseID:&self.databaseInfo->database_id()
-                               token:(token.is_valid() ? token.token() : absl::string_view())];
+                               token:(token.user().is_authenticated() ? token.token() : absl::string_view())];
   FSTAssert(_callbackFilter == nil, @"GRX Filter must be nil");
   _callbackFilter = [[FSTCallbackFilter alloc] initWithStream:self];
   [_rpc startWithWriteable:_callbackFilter];