[webcrypto] Make the import algorithm a required parameter.

public/platform/WebCrypto.h

Index: public/platform/WebCrypto.h
diff --git a/public/platform/WebCrypto.h b/public/platform/WebCrypto.h
index 7b56f4ef7bfd391eb1f6af186fb6449b04f3d94d..605d43bd73fd7a6e4660613d02575beb2e1c7079 100644
--- a/public/platform/WebCrypto.h
+++ b/public/platform/WebCrypto.h
@@ -147,8 +147,6 @@ public:
     //   * All WebCryptoKeys are guaranteeed to be !isNull().
     //
     //   * All WebCryptoAlgorithms are guaranteed to be !isNull()
-    //     unless noted otherwise. Being "null" means that it was unspecified
-    //     by the caller.
     //
     //   * Look to the Web Crypto spec for an explanation of the parameter. The
     //     method names here have a 1:1 correspondence with those of
@@ -175,11 +173,9 @@ public:
     virtual void verifySignature(const WebCryptoAlgorithm&, const WebCryptoKey&, const unsigned char* signature, unsigned signatureSize, const unsigned char* data, unsigned dataSize, WebCryptoResult result) { result.completeWithError(); }
     virtual void digest(const WebCryptoAlgorithm&, const unsigned char* data, unsigned dataSize, WebCryptoResult result) { result.completeWithError(); }
     virtual void generateKey(const WebCryptoAlgorithm&, bool extractable, WebCryptoKeyUsageMask, WebCryptoResult result) { result.completeWithError(); }
-    // It is possible for the WebCryptoAlgorithm to be "isNull()"
     virtual void importKey(WebCryptoKeyFormat, const unsigned char* keyData, unsigned keyDataSize, const WebCryptoAlgorithm&, bool extractable, WebCryptoKeyUsageMask, WebCryptoResult result) { result.completeWithError(); }
     virtual void exportKey(WebCryptoKeyFormat, const WebCryptoKey&, WebCryptoResult result) { result.completeWithError(); }
     virtual void wrapKey(WebCryptoKeyFormat, const WebCryptoKey& key, const WebCryptoKey& wrappingKey, const WebCryptoAlgorithm&, WebCryptoResult result) { result.completeWithError(); }
-    // It is possible that unwrappedKeyAlgorithm.isNull()
     virtual void unwrapKey(WebCryptoKeyFormat, const unsigned char* wrappedKey, unsigned wrappedKeySize, const WebCryptoKey&, const WebCryptoAlgorithm& unwrapAlgorithm, const WebCryptoAlgorithm& unwrappedKeyAlgorithm, bool extractable, WebCryptoKeyUsageMask, WebCryptoResult result) { result.completeWithError(); }
 
     // This is the one exception to the "Completing the request" guarantees