WebCrypto: [refactor] Use "unsigned" rather than "size_t" for buffer sizes.

Source/modules/crypto/SubtleCrypto.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 57 matching lines @@
     }
 
     WebKit::WebCryptoAlgorithm algorithm;
     if (!normalizeAlgorithm(rawAlgorithm, operationType, algorithm, es))
         return ScriptPromise();
 
     if (requiresKey && !key->canBeUsedForAlgorithm(algorithm, operationType, es))
         return ScriptPromise();
 
     const unsigned char* data = static_cast<const unsigned char*>(dataBuffer->baseAddress());
-    size_t dataSize = dataBuffer->byteLength();
+    unsigned dataSize = dataBuffer->byteLength();
 
     RefPtr<CryptoResult> result = CryptoResult::create();
 
     switch (operationType) {
     case Encrypt:
         WebKit::Platform::current()->crypto()->encrypt(algorithm, key->key(), data, dataSize, result->result());
         break;
     case Decrypt:
         WebKit::Platform::current()->crypto()->decrypt(algorithm, key->key(), data, dataSize, result->result());
         break;
@@ skipping 102 matching lines @@
         es.throwDOMException(NotSupportedError, "key is not extractable");
         return ScriptPromise();
     }
 
     RefPtr<CryptoResult> result = CryptoResult::create();
     WebKit::Platform::current()->crypto()->exportKey(format, key->key(), result->result());
     return result->promise();
 }
 
 } // namespace WebCore