Tidy up CompositorWorkerManager unit tests.

Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.cpp

Index: Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.cpp
diff --git a/Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.cpp b/Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.cpp
index f42f49f4232a23a15a6111713127fb6fe0680579..ca664be8e0917f94630d2d405bf61a6929e3e5dd 100644
--- a/Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.cpp
+++ b/Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.cpp
@@ -43,7 +43,10 @@ const char* ServiceWorkerGlobalScopeClient::supplementName()
 
 ServiceWorkerGlobalScopeClient* ServiceWorkerGlobalScopeClient::from(ExecutionContext* context)
 {
-    return static_cast<ServiceWorkerGlobalScopeClient*>(WillBeHeapSupplement<WorkerClients>::from(toWorkerGlobalScope(context)->clients(), supplementName()));
+    ASSERT(context->isWorkerGlobalScope());

[haraken, 2015/06/07 23:37:11]

You can remove this. This check is already done in toWorkerGlobalScope(context).

[sof, 2015/06/08 08:18:16]

Removed (here&elsewhere.)

+    WorkerClients* clients = toWorkerGlobalScope(context)->clients();
+    ASSERT(clients);

[kinuko, 2015/06/08 04:36:59]

Should these rather return nullptr here if we allow null-clients, or could we
add an assertion like ASSERT(m_workerClients || isCompositorWorkerGlobalScope())
(with a comment to note that CW doesn't expose APIs that require clients impl)
in WorkerGlobalScope's ctor so that intention (for allowing null clients)
becomes clearer?

[sof, 2015/06/08 08:18:16]

But ServiceWorkerGlobalScopeClient isn't exposed to CompositorWorker?

(Unit test uses of workers will also supply a null WorkerClients.)

+    return static_cast<ServiceWorkerGlobalScopeClient*>(WillBeHeapSupplement<WorkerClients>::from(clients, supplementName()));
 }
 
 void provideServiceWorkerGlobalScopeClientToWorker(WorkerClients* clients, PassOwnPtrWillBeRawPtr<ServiceWorkerGlobalScopeClient> client)