doc: Fix incorrect syntax

These are not considered errors in jsduck 4.x but are in 5.x.

Though we don't specifically want to support 5.x yet, these are
actually genuine errors that were already causing incorrect
documentation to be generated, even under 4.x (it just doesn't
warn for these under 4.x).

Not from 5.x warnings, but fixed while at it:
* Removed more redundant @method
* Added a missing @returns for ve.Range#flip
* Added newline at EOF

Change-Id: Idc22b46b082a813e8e1761403e1ebf908bf690c4
Merge "doc: Fix incorrect syntax"