Make CryptoResultImpl not to use WeakPtr.

Source/bindings/core/v8/ScriptPromise.h

 /*
  * 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 108 matching lines @@
     // This is a utility class intended to be used internally.
     // ScriptPromiseResolver is for general purpose.
     class InternalResolver final {
     public:
         explicit InternalResolver(ScriptState*);
         v8::Local<v8::Promise> v8Promise() const;
         ScriptPromise promise() const;
         void resolve(v8::Local<v8::Value>);
         void reject(v8::Local<v8::Value>);
         void clear() { m_resolver.clear(); }
+        bool cleared() const { return m_resolver.isEmpty(); }
 
     private:
         ScriptValue m_resolver;
     };
 
 private:
     RefPtr<ScriptState> m_scriptState;
     ScriptValue m_promise;
 };
 
 } // namespace blink
 
 
 #endif // ScriptPromise_h