Bug 1499462: Remove dead failure handling and comments from ThrottledEventQueue::Create. r=froydnj

Differential Revision: https://phabricator.services.mozilla.com/D8890

--HG--
extra : moz-landing-system : lando

xpcom/threads/ThrottledEventQueue.cpp

@@ -308,9 +308,6 @@ ThrottledEventQueue::Create(nsISerialEventTarget* aBaseTarget)
   MOZ_ASSERT(aBaseTarget);
 
   RefPtr<Inner> inner = Inner::Create(aBaseTarget);
-  if (NS_WARN_IF(!inner)) {
-    return nullptr;
-  }
 
   RefPtr<ThrottledEventQueue> ref =
     new ThrottledEventQueue(inner.forget());

xpcom/threads/ThrottledEventQueue.h

@@ -64,8 +64,7 @@ class ThrottledEventQueue final : public nsISerialEventTarget
   ~ThrottledEventQueue() = default;
 
 public:
-  // Attempt to create a ThrottledEventQueue for the given target.  This
-  // may return nullptr if the browser is already shutting down.
+  // Create a ThrottledEventQueue for the given target.
   static already_AddRefed<ThrottledEventQueue>
   Create(nsISerialEventTarget* aBaseTarget);