Fix auto upgrade for oauth provider (#824)

Author: renkelvin

Auth/FirebaseAuthUI/FUIAuth.m

@@ -237,15 +237,11 @@ - (void)autoUpgradeAccountWithProviderUI:(id<FUIAuthProvider>)providerUI
     if (error) {
       // Check for "credential in use" conflict error and handle appropriately.
       if (error.code == FIRAuthErrorCodeCredentialAlreadyInUse) {
-        FIRAuthCredential *newCredential = credential;
-        // Check for and handle special case for Phone Auth Provider.
-        if (providerUI.providerID == FIRPhoneAuthProviderID) {
-          // Obtain temporary Phone Auth credential.
-          newCredential = error.userInfo[FIRAuthErrorUserInfoUpdatedCredentialKey];
+        FIRAuthCredential *newCredential = error.userInfo[FIRAuthErrorUserInfoUpdatedCredentialKey];
+        NSDictionary *userInfo = @{ };
+        if (newCredential) {
+          userInfo = @{ FUIAuthCredentialKey : newCredential };
         }
-        NSDictionary *userInfo = @{
-          FUIAuthCredentialKey : newCredential,
-        };
         NSError *mergeError = [FUIAuthErrorUtils mergeConflictErrorWithUserInfo:userInfo
                                                                 underlyingError:error];
         [self completeSignInWithResult:authResult

EmailAuth/FirebaseEmailAuthUI/FUIEmailAuth.m

@@ -221,7 +221,7 @@ - (void)signInWithDefaultValue:(nullable NSString *)defaultValue
 }
 
 - (void)signOut {
-
+  return;
 }
 
 - (BOOL)handleOpenURL:(NSURL *)URL sourceApplication:(nullable NSString *)sourceApplication {

OAuth/FirebaseOAuthUI/FUIOAuth.m

@@ -284,16 +284,7 @@ - (void)signInWithDefaultValue:(nullable NSString *)defaultValue
 }
 
 - (void)signOut {
-  FIRUser *user = _authUI.auth.currentUser;
-  __weak UIViewController *weakController = self.presentingViewController;
-  [user deleteWithCompletion:^(NSError * _Nullable error) {
-    if (error) {
-      __strong UIViewController *presentingViewController = weakController;
-      [FUIAuthBaseViewController showAlertWithMessage:error.localizedDescription
-                             presentingViewController:presentingViewController];
-      return;
-    }
-  }];
+  return;
 }
 
 - (BOOL)handleOpenURL:(NSURL *)URL sourceApplication:(nullable NSString *)sourceApplication {

PhoneAuth/FirebasePhoneAuthUI/FUIPhoneAuth.m

@@ -165,6 +165,7 @@ - (void)signInWithDefaultValue:(nullable NSString *)defaultValue
 }
 
 - (void)signOut {
+  return;
 }
 
 - (BOOL)handleOpenURL:(NSURL *)URL sourceApplication:(nullable NSString *)sourceApplication {