Bug 1256428 P19 Address ServiceWorkerUnregisterJob review feedback. r=jdm

dom/workers/ServiceWorkerUnregisterJob.cpp

@@ -26,6 +26,7 @@ ServiceWorkerUnregisterJob::GetResult() const
   AssertIsOnMainThread();
   return mResult;
 }
+
 ServiceWorkerUnregisterJob::~ServiceWorkerUnregisterJob()
 {
 }
@@ -40,6 +41,11 @@ ServiceWorkerUnregisterJob::AsyncExecute()
     return;
   }
 
+  // Step 1 of the Unregister algorithm requires checking that the
+  // client origin matches the scope's origin.  We perform this in
+  // registration->update() method directly since we don't have that
+  // client information available here.
+
   RefPtr<ServiceWorkerManager> swm = ServiceWorkerManager::GetInstance();
 
   // "Let registration be the result of running [[Get Registration]]