Function gets redefined, leading to very messy/weird generated .d.ts file

[mtaran-google]

Ran clutz on some externs for CodeMirror. This ended up creating

declare namespace ಠ_ಠ.clutz.CodeMirror {
  type HintFunction = Function ;
}

but then clutz also renamed every other use of Function in the file to ಠ_ಠ.clutz.CodeMirror.HintFunction, which resulted in kinda ridiculous-looking code :)