Credential Manager: Pass the correct credential type to the embedder.

Source/platform/exported/WebLocalCredential.cpp

Index: Source/platform/exported/WebLocalCredential.cpp
diff --git a/Source/platform/exported/WebLocalCredential.cpp b/Source/platform/exported/WebLocalCredential.cpp
index 26d09c5795e1bb202c345507795297bd3aa4cf4e..84c282e20f971fa46d16c4d6f38076e40aba2afc 100644
--- a/Source/platform/exported/WebLocalCredential.cpp
+++ b/Source/platform/exported/WebLocalCredential.cpp
@@ -24,5 +24,16 @@ WebString WebLocalCredential::password() const
     return static_cast<PlatformLocalCredential*>(m_platformCredential.get())->password();
 }
 
+WebLocalCredential::WebLocalCredential(PlatformCredential* credential)
+    : WebCredential(credential)
+{
+}
+
+WebLocalCredential& WebLocalCredential::operator=(PlatformCredential* credential)
+{
+    m_platformCredential = credential;
+    return *this;
+}
+
 } // namespace blink