[webcrypto] Replace KeyAlgorithm interfaces with an Object.

Source/platform/exported/WebCryptoKeyAlgorithm.cpp

Index: Source/platform/exported/WebCryptoKeyAlgorithm.cpp
diff --git a/Source/platform/exported/WebCryptoKeyAlgorithm.cpp b/Source/platform/exported/WebCryptoKeyAlgorithm.cpp
index 83f7d90c9cad244666417cd1007efbe7557b806b..1648380c10dc3fba795ed0fa9e10c00e1096c973 100644
--- a/Source/platform/exported/WebCryptoKeyAlgorithm.cpp
+++ b/Source/platform/exported/WebCryptoKeyAlgorithm.cpp
@@ -131,6 +131,13 @@ WebCryptoRsaHashedKeyAlgorithmParams* WebCryptoKeyAlgorithm::rsaHashedParams() c
     return 0;
 }
 
+void WebCryptoKeyAlgorithm::writeToDictionary(WebCryptoKeyAlgorithmDictionary* dict) const
+{
+    ASSERT(!isNull());
+    dict->setString("name", WebCryptoAlgorithm::lookupAlgorithmInfo(id())->name);
+    m_private->params.get()->writeToDictionary(dict);
+}
+
 void WebCryptoKeyAlgorithm::assign(const WebCryptoKeyAlgorithm& other)
 {
     m_private = other.m_private;