Delete type declaration files without any content

[stramel]

You can see more what I mean here: https://github.com/PolymerElements/marked-element/pull/88/files#diff-8c66e52d6509ca0676ce2b5fbc5e4c4e

/**
 * DO NOT EDIT
 *
 * This file was automatically generated by
 *   https://github.com/Polymer/gen-typescript-declarations
 *
 * To modify these typings, edit the source file(s):
 *   marked-import.html
 */

I have removed the reference that was there in the gen-tsd.json.

{
  "removeReferences": [
    "../marked/lib/marked.d.ts"
  ]
}

[aomarks]

We actually prefer to keep these. The reason is that this tool generally mirrors the HTML import graph in it the /// <reference ... statements it inserts. It's simpler to just let files with no declarations exist as empty files, than for all of the other repos that depend on this one to know to remove that reference.