Quota: Add null check

Source/modules/quota/DeprecatedStorageQuota.cpp

Index: Source/modules/quota/DeprecatedStorageQuota.cpp
diff --git a/Source/modules/quota/DeprecatedStorageQuota.cpp b/Source/modules/quota/DeprecatedStorageQuota.cpp
index cb55c3c6af70eeaf7f700b7b361856ee4a922486..6bbdea7499937a3d5e9dc69e9f1cafdac147c98e 100644
--- a/Source/modules/quota/DeprecatedStorageQuota.cpp
+++ b/Source/modules/quota/DeprecatedStorageQuota.cpp
@@ -85,7 +85,13 @@ void DeprecatedStorageQuota::requestQuota(ExecutionContext* executionContext, un
         return;
     }
 
-    StorageQuotaClient::from(executionContext)->requestQuota(executionContext, storageType, newQuotaInBytes, successCallback, errorCallback);
+    StorageQuotaClient* client = StorageQuotaClient::from(executionContext);
+    if (!client) {
+        executionContext->postTask(StorageErrorCallback::CallbackTask::create(errorCallback, NotSupportedError));
+        return;
+    }
+
+    client->requestQuota(executionContext, storageType, newQuotaInBytes, successCallback, errorCallback);
 }
 
 DeprecatedStorageQuota::~DeprecatedStorageQuota()