[cmv4] Add Next Line to Selection does not work correctly with Tabs

[redmunds]

1. Start with this block of code which is indented and aligned with Tabs (tabSize: 4).

   var Global                  = require("utils/Global"),
       AppInit                 = require("utils/AppInit"),
       LanguageManager         = require("language/LanguageManager"),
       ProjectManager          = require("project/ProjectManager"),
       DocumentManager         = require("document/DocumentManager"),
       EditorManager           = require("editor/EditorManager"),
       CSSInlineEditor         = require("editor/CSSInlineEditor"),
       JSUtils                 = require("language/JSUtils");
   

2. Place cursor in first line immediately before =

3. Press Shift-Alt-Down a few times

Results:
Cursors are not vertically aligned. Position seems to be determined by number of chars, not visual placement.

Expected:
New cursor is added directly below line above

[njx]

Closing as fixed.