Fix bug where starting the email flow would show a useless progress dialog

Author: SUPERCILEX

auth/src/main/java/com/firebase/ui/auth/ui/idp/AuthMethodPickerActivity.java

@@ -114,7 +114,9 @@ private void populateIdpList(List<IdpConfig> providers) {
             loginButton.setOnClickListener(new View.OnClickListener() {
                 @Override
                 public void onClick(View view) {
-                    mActivityHelper.showLoadingDialog(R.string.progress_dialog_loading);
+                    if (provider instanceof IdpProvider) {
+                        mActivityHelper.showLoadingDialog(R.string.progress_dialog_loading);
+                    }
                     provider.startLogin(AuthMethodPickerActivity.this);
                 }
             });