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

Source/modules/webdatabase/SQLVoidCallback.idl

Index: Source/modules/webdatabase/SQLVoidCallback.idl
diff --git a/Source/core/html/VoidCallback.idl b/Source/modules/webdatabase/SQLVoidCallback.idl
similarity index 97%
copy from Source/core/html/VoidCallback.idl
copy to Source/modules/webdatabase/SQLVoidCallback.idl
index d403ecc48c1ca76dbd05bcca9ee8f29b0190b53c..5f69be5220439e5ba608553e493937ee27b04d68 100644
--- a/Source/core/html/VoidCallback.idl
+++ b/Source/modules/webdatabase/SQLVoidCallback.idl
@@ -23,6 +23,6 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-callback interface VoidCallback {
+callback interface SQLVoidCallback {
     boolean handleEvent();
 };