Have ScriptPromiseResolver on the Oilpan heap always.

Source/modules/presentation/PresentationRequest.cpp

Index: Source/modules/presentation/PresentationRequest.cpp
diff --git a/Source/modules/presentation/PresentationRequest.cpp b/Source/modules/presentation/PresentationRequest.cpp
index 0b4bf091b03ab8548324f759c5d0a2eb17bf282c..19af64082ade0d18825c3d7bc300a6baa0d4eb36 100644
--- a/Source/modules/presentation/PresentationRequest.cpp
+++ b/Source/modules/presentation/PresentationRequest.cpp
@@ -68,7 +68,7 @@ bool PresentationRequest::hasPendingActivity() const
 
 ScriptPromise PresentationRequest::start(ScriptState* scriptState)
 {
-    RefPtrWillBeRawPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
+    ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     WebPresentationClient* client = presentationClient(executionContext());
@@ -83,7 +83,7 @@ ScriptPromise PresentationRequest::start(ScriptState* scriptState)
 
 ScriptPromise PresentationRequest::join(ScriptState* scriptState, const String& id)
 {
-    RefPtrWillBeRawPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
+    ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     WebPresentationClient* client = presentationClient(executionContext());
@@ -98,7 +98,7 @@ ScriptPromise PresentationRequest::join(ScriptState* scriptState, const String&
 
 ScriptPromise PresentationRequest::getAvailability(ScriptState* scriptState)
 {
-    RefPtrWillBeRawPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
+    ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     WebPresentationClient* client = presentationClient(executionContext());