Remove ENABLE(FILE_SYSTEM) compile-time flag.

Source/WebCore/Modules/filesystem/AsyncFileWriter.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef AsyncFileWriter_h
 #define AsyncFileWriter_h
 
-#if ENABLE(FILE_SYSTEM)
-
 #include <wtf/RefCounted.h>
 #include <wtf/text/WTFString.h>
 
 namespace WebCore {
 
 class Blob;
 
 class AsyncFileWriter {
 public:
     virtual ~AsyncFileWriter() { }
 
     virtual void write(long long position, Blob* data) = 0;
     virtual void truncate(long long length) = 0;
     virtual void abort() = 0;
     virtual bool waitForOperationToComplete() // Needed for FileWriterSync only.
     {
         return false;
     }
 };
 
 } // namespace
 
-#endif // ENABLE(FILE_SYSTEM)
-
 #endif // AsyncFileWriter_h