Reliably cancel in-progress CryptoResult(Impl) upon shutdown.

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 377 matching lines @@
     if (!baseKey->canBeUsedForAlgorithm(algorithm, WebCryptoKeyUsageDeriveBits, result.get()))
         return promise;
 
     histogramAlgorithmAndKey(scriptState->executionContext(), algorithm, baseKey->key());
     Platform::current()->crypto()->deriveBits(algorithm, baseKey->key(), lengthBits, result->result());
     return promise;
 }
 
 ScriptPromise SubtleCrypto::deriveKey(ScriptState* scriptState, const AlgorithmIdentifier& rawAlgorithm, CryptoKey* baseKey, const AlgorithmIdentifier& rawDerivedKeyType, bool extractable, const Vector<String>& rawKeyUsages)
 {
-    RefPtr<CryptoResultImpl> result = CryptoResultImpl::create(scriptState);
+    RefPtrWillBeRawPtr<CryptoResultImpl> result = CryptoResultImpl::create(scriptState);
     ScriptPromise promise = result->promise();
 
     if (!canAccessWebCrypto(scriptState, result.get()))
         return promise;
 
     WebCryptoKeyUsageMask keyUsages;
     if (!CryptoKey::parseUsageMask(rawKeyUsages, keyUsages, result.get()))
         return promise;
 
     WebCryptoAlgorithm algorithm;
@@ skipping 11 matching lines @@
     if (!parseAlgorithm(rawDerivedKeyType, WebCryptoOperationGetKeyLength, keyLengthAlgorithm, result.get()))
         return promise;
 
     histogramAlgorithmAndKey(scriptState->executionContext(), algorithm, baseKey->key());
     histogramAlgorithm(scriptState->executionContext(), importAlgorithm);
     Platform::current()->crypto()->deriveKey(algorithm, baseKey->key(), importAlgorithm, keyLengthAlgorithm, extractable, keyUsages, result->result());
     return promise;
 }
 
 } // namespace blink