Make CryptoResultImpl not to use WeakPtr.

Source/modules/crypto/CryptoResultImpl.h

Index: Source/modules/crypto/CryptoResultImpl.h
diff --git a/Source/modules/crypto/CryptoResultImpl.h b/Source/modules/crypto/CryptoResultImpl.h
index 3ea352cb662d7b5bb8d5a35704e30b9bfeaeb49d..b8e3089e8d5ef5f9a6ec64c65d79012f91f2672e 100644
--- a/Source/modules/crypto/CryptoResultImpl.h
+++ b/Source/modules/crypto/CryptoResultImpl.h
@@ -72,12 +72,15 @@ public:
     ScriptPromise promise();
 
 private:
-    class WeakResolver;
+    class Resolver;
     explicit CryptoResultImpl(ScriptState*);
 
+    void clearResolver();
     void cancel();
 
-    WeakPtr<ScriptPromiseResolver> m_resolver;
+    // FIXME: ScriptPromiseResolver should not be exported.
+    // Instead, use ScriptPromise.
+    ScriptPromiseResolver* m_resolver;
     volatile int m_cancelled;
 };