Webappsstore.sqlite
From MozillaZine Knowledge Base
webappsstore.sqlite contains DOM Storage data. This data is set by web sites much in the same way as cookies.
Editing
webappsstore.sqlite is a binary SQLite file and should not be edited manually.
Moving
This file can be moved to a different profile without any extra effort.
Deleting
Deleting webappsstore.sqlite will delete any data web sites have stored there. A new file will be created when it is needed.