Web SQL: Make sure DatabaseManager is used only in the main thread.

Source/modules/webdatabase/AbstractDatabaseServer.h

Index: Source/modules/webdatabase/AbstractDatabaseServer.h
diff --git a/Source/modules/webdatabase/AbstractDatabaseServer.h b/Source/modules/webdatabase/AbstractDatabaseServer.h
index f82ce88f551f5437e184f04b8ff7fcc565cbbb2f..5022a828dc18b3ff3176c5f7daad249b8542957b 100644
--- a/Source/modules/webdatabase/AbstractDatabaseServer.h
+++ b/Source/modules/webdatabase/AbstractDatabaseServer.h
@@ -46,8 +46,6 @@ public:
         const String& name, const String& expectedVersion, const String& displayName, unsigned long estimatedSize,
         bool setVersionInNewDatabase, DatabaseError&, String& errorMessage) = 0;
 
-    virtual void closeDatabasesImmediately(const String& originIdentifier, const String& name) = 0;
-
 protected:
     AbstractDatabaseServer() { }
     virtual ~AbstractDatabaseServer() { }