Generate toFile() instead of manual functions.
https://bugs.webkit.org/show_bug.cgi?id=136207

Reviewed by Darin Adler.

No new tests, no behavior changes.

* fileapi/Blob.h: Define BLOB_TYPE_CASTS.
* fileapi/File.h: Use BLOB_TYPE_CASTS to generate toFile().
(WebCore::toFile): Deleted.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@172951 268f45cc-cd09-0410-ab3c-d52691b4dbfc