Decouple FileSystem and WebSQL callbacks from VoidCallback and it non-refcounted

Source/modules/filesystem/FileSystemVoidCallback.idl

Index: Source/modules/filesystem/FileSystemVoidCallback.idl
diff --git a/Source/core/html/VoidCallback.idl b/Source/modules/filesystem/FileSystemVoidCallback.idl
similarity index 96%
copy from Source/core/html/VoidCallback.idl
copy to Source/modules/filesystem/FileSystemVoidCallback.idl
index d403ecc48c1ca76dbd05bcca9ee8f29b0190b53c..5d7eb44f447c7744603ae62dcd283ac9025f609d 100644
--- a/Source/core/html/VoidCallback.idl
+++ b/Source/modules/filesystem/FileSystemVoidCallback.idl
@@ -23,6 +23,6 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-callback interface VoidCallback {
+callback interface FileSystemVoidCallback {
     boolean handleEvent();
 };