Credential Management: Add 'Credential::type' attribute.

LayoutTests/http/tests/credentialmanager/federatedcredential-basics.html

Index: LayoutTests/http/tests/credentialmanager/federatedcredential-basics.html
diff --git a/LayoutTests/http/tests/credentialmanager/federatedcredential-basics.html b/LayoutTests/http/tests/credentialmanager/federatedcredential-basics.html
index 5a0b75f62013c807c427e83a154bac3c7f0c3e19..5c9020beb43d5d78808dedc4f951d5907bc44f32 100644
--- a/LayoutTests/http/tests/credentialmanager/federatedcredential-basics.html
+++ b/LayoutTests/http/tests/credentialmanager/federatedcredential-basics.html
@@ -19,13 +19,15 @@ test(function() {
         id: 'string',
         name: 'string',
         avatarURL: 'string',
-        provider: 'string'
+        provider: 'string',
+        type: 'string'
     });
 
     assert_equals(credential.id, 'id');
     assert_equals(credential.name, 'name');
     assert_equals(credential.avatarURL, 'https://example.test/icon.png');
     assert_equals(credential.provider, 'https://federation.test/');
+    assert_equals(credential.type, 'federated');
 }, 'Interfaces and attributes of FederatedCredential');
 
 test(function() {
@@ -39,6 +41,7 @@ test(function() {
     assert_equals(credential.name, 'name');
     assert_equals(credential.avatarURL, '');
     assert_equals(credential.provider, 'https://federation.test/');
+    assert_equals(credential.type, 'federated');
 }, 'Interfaces and attributes of FederatedCredential');
 
 test(function() {
@@ -51,6 +54,7 @@ test(function() {
     assert_equals(credential.name, '');
     assert_equals(credential.avatarURL, '');
     assert_equals(credential.provider, 'https://federation.test/');
+    assert_equals(credential.type, 'federated');
 }, 'Interfaces and attributes of FederatedCredential');
 
 test(function() {