[part 1] Make classes and structures in modules/ fast-allocated.

Source/modules/filesystem/DevToolsHostFileSystem.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DevToolsHostFileSystem_h
 #define DevToolsHostFileSystem_h
 
 #include "platform/heap/Handle.h"
+#include "wtf/Allocator.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class DOMFileSystem;
 class DevToolsHost;
 
 class DevToolsHostFileSystem {
+    STATIC_ONLY(DevToolsHostFileSystem);
 public:
     static DOMFileSystem* isolatedFileSystem(DevToolsHost&, const String& fileSystemName, const String& rootURL);
     static void upgradeDraggedFileSystemPermissions(DevToolsHost&, DOMFileSystem*);
-private:
-    DevToolsHostFileSystem();
-    ~DevToolsHostFileSystem();
 };
 
 } // namespace blink
 
 #endif // !defined(DevToolsHostFileSystem_h)