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

Source/modules/serviceworkers/ExtendableEvent.h

Index: Source/modules/serviceworkers/ExtendableEvent.h
diff --git a/Source/modules/serviceworkers/ExtendableEvent.h b/Source/modules/serviceworkers/ExtendableEvent.h
index 585bc85111c35225324508c5775778f413fcca3e..21781095184201dd2a564260e87e4a480edbfebe 100644
--- a/Source/modules/serviceworkers/ExtendableEvent.h
+++ b/Source/modules/serviceworkers/ExtendableEvent.h
@@ -49,7 +49,7 @@ public:
 
     ~ExtendableEvent() override;
 
-    void waitUntil(ScriptState*, const ScriptValue&, ExceptionState&);
+    void waitUntil(ScriptState*, ScriptPromise&, ExceptionState&);

[yhirano, 2015/07/27 12:21:24]

Can you use |ScriptPromise| instead of |ScriptPromise&|?

[jungkees, 2015/07/27 12:37:49]

Sure, but could you explain why? Both scriptPromise and exceptionState are
passed references. Is there any case where the object created in V8 layer
destroyed before the object passed to Blink layer? If it should, I'll probably
have to change the same for FetchEvent.respondWith code where I used references.
Thanks! 

[yhirano, 2015/07/27 12:45:32]

ScriptPromise is a value and copying it is not expensive. I would rather use
value than non-const reference in such cases. ExceptionState is different: It is
not copyable, and that non-const reference intends to update the state.

I'm sorry I overlooked the point in the last CL.

[jungkees, 2015/07/27 14:23:33]

Agreed. Thanks for the explanation!
I'll address this point there too.

 
     const AtomicString& interfaceName() const override;
     DECLARE_VIRTUAL_TRACE();