Fix to support drag-and-drop of filesystem files

Fill File::m_name with the last path component of the filesystem URL.
Append filesystem URL in XMLHttpRequest::send.
Add a new storage type "StorageTypeFileSystemFile" to WebDragData.

BUG=126766

Review URL: https://codereview.chromium.org/228003004

git-svn-id: svn://svn.chromium.org/blink/trunk@171136 bbb929c8-8fbe-4397-9dbb-9b2b20218538