[BUGFIX beta]

In 1.6 Ember.computed.empty was updated to
automatically respect arrays without forcing
users to use array.[] as the dependent key.

Ember.computed.notEmpty was not updated.

This commit fixes that.
Merge pull request #5361 from jeffreybiles/computed-not-empty-array-does-not-require-brackets

[BUGFIX beta] Computed not empty array does not require brackets