[vim] remove visualBlock check in exitVisualMode
[vim] Removed defunct comment.

@mightyguava fixed this issue in https://github.com/marijnh/CodeMirror/commit/45fe0a109d02f682ee435a4093843d5124cf95b9
Fix gutter width compensation in calculateScrollPos

Issue #2745
Less fragile way to deal with updating the scrollbar during editor width changes

Issue #2745