Have ScriptPromiseResolver on the Oilpan heap always.

Source/platform/CryptoResult.h

Index: Source/platform/CryptoResult.h
diff --git a/Source/platform/CryptoResult.h b/Source/platform/CryptoResult.h
index 3ccff2e211e705773d5ab873db418b2080aa680b..025c329c24414221c3a599fad681b30b36a97388 100644
--- a/Source/platform/CryptoResult.h
+++ b/Source/platform/CryptoResult.h
@@ -32,12 +32,11 @@
 #define CryptoResult_h
 
 #include "public/platform/WebCrypto.h"
-#include "wtf/ThreadSafeRefCounted.h"
 
 namespace blink {
 
 // Receives notification of completion of the crypto operation.
-class CryptoResult : public ThreadSafeRefCounted<CryptoResult> {
+class CryptoResult : public GarbageCollectedFinalized<CryptoResult> {
 public:
     virtual ~CryptoResult() { }
 
@@ -53,6 +52,8 @@ public:
     {
         return WebCryptoResult(this);
     }
+
+    DEFINE_INLINE_VIRTUAL_TRACE() { }
 };
 
 } // namespace blink