Gerunds not labelled correctly

[matthewtoast]

The parser seems to incorrectly label gerunds.

For example:

require('en-parse').parse(
  ['VBG', 'VBZ', 'NN'],
  ['playing', 'is', 'fun']
)
// output:
[ { label: 'ROOT', type: 'VP', parent: -1 },
  { label: 'NSUBJ', type: 'VP', parent: 0 },
  { label: 'DOBJ', type: 'NP', parent: 1 } ]

In this case I would expect:

[ { label: 'NSUBJ', type: 'VP', parent: 1 }, // playing
  { label: 'ROOT', type: 'VP', parent: -1 }, // is
  { label: 'DOBJ', type: 'NP', parent: 1 } ] // fun