Clean-up some Windows FILES.cfg items.
Clean-up some Windows FILES.cfg items.

- Add missing devtools_frontend.zip in prep for removing the hard-coded
  reference from archive_build.py.
- mini_installer.exe exists on both dev and official builds. Hard-coded
  reference in archive_build.py will be removed.
- Remove old 'symbols' filegroup from official-only files, since that is
  only used in archive_build.py (and even there it will go away soon).

Review URL: https://chromiumcodereview.appspot.com/10154011

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@134106 0039d316-1c4b-4281-b951-d872f2087c98

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