Service Worker: Correct Web IDL of ExtendableEvent.waitUntil method.

Source/modules/serviceworkers/WaitUntilObserver.cpp

Index: Source/modules/serviceworkers/WaitUntilObserver.cpp
diff --git a/Source/modules/serviceworkers/WaitUntilObserver.cpp b/Source/modules/serviceworkers/WaitUntilObserver.cpp
index 4cb47eae9d6767d8b8c2403f238c65eaa6bc72d3..1672b6c66f04f0dd6bbff0151a8cc8be6ce80b71 100644
--- a/Source/modules/serviceworkers/WaitUntilObserver.cpp
+++ b/Source/modules/serviceworkers/WaitUntilObserver.cpp
@@ -107,7 +107,7 @@ void WaitUntilObserver::didDispatchEvent(bool errorOccurred)
     m_eventDispatched = true;
 }
 
-void WaitUntilObserver::waitUntil(ScriptState* scriptState, const ScriptValue& value, ExceptionState& exceptionState)
+void WaitUntilObserver::waitUntil(ScriptState* scriptState, ScriptPromise scriptPromise, ExceptionState& exceptionState)
 {
     if (m_eventDispatched) {
         exceptionState.throwDOMException(InvalidStateError, "The event handler is already finished.");
@@ -126,7 +126,7 @@ void WaitUntilObserver::waitUntil(ScriptState* scriptState, const ScriptValue& v
         m_consumeWindowInteractionTimer.startOneShot(windowInteractionTimeout(), FROM_HERE);
 
     incrementPendingActivity();
-    ScriptPromise::cast(scriptState, value).then(
+    scriptPromise.then(
         ThenFunction::createFunction(scriptState, this, ThenFunction::Fulfilled),
         ThenFunction::createFunction(scriptState, this, ThenFunction::Rejected));
 }