Search hilighting does not update properly when changing the visual region.

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Enable hlsearch and search for a pattern such as \%V.\%V
2. Start a new visual selection on a different line

What is the expected output? What do you see instead?

Expected output is that search highlighting will clear in the region of the 
former selection that nolonger matches the pattern. Actual result is that it 
only clears on lines that are updated (i.e. the cursor is moved into them while 
continuing to extend the visual area.)


What version of the product are you using? On what operating system?

Verified on MacVim 7.4 and system default Vim 7.3 on OSX.

Original issue reported on code.google.com by random832@gmail.com on 5 May 2015 at 2:55