Remove ENABLE(FILE_SYSTEM) compile-time flag.

Source/WebCore/Modules/filesystem/FileWriter.idl

 /*
  * Copyright (C) 2010 Google Inc.  All rights reserved.
  * Copyright (C) 2011 Apple 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.
@@ skipping 12 matching lines @@
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * 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.
  */
 
 [
-    Conditional=FILE_SYSTEM,
     ActiveDOMObject,
     CallWith=ScriptExecutionContext,
     EventTarget
 ] interface FileWriter {
     // ready states
     const unsigned short INIT = 0;
     const unsigned short WRITING = 1;
     const unsigned short DONE = 2;
     readonly attribute unsigned short readyState;
 
@@ skipping 18 matching lines @@
     // EventTarget interface
     void addEventListener(DOMString type,
                           EventListener listener,
                           [Optional] boolean useCapture);
     void removeEventListener(DOMString type,
                              EventListener listener,
                              [Optional] boolean useCapture);
     boolean dispatchEvent(Event evt)
         raises(EventException);
 };