RFR (XXS): 8183006: Remove unused IterateOopClosureRegionClosure

[Thomas Schatzl]

Hi all,

  subject says it all.

I think one Reviewer should be sufficient for this change.

CR:
https://bugs.openjdk.java.net/browse/JDK-8183006
Webrev:
http://cr.openjdk.java.net/~tschatzl/8183006/webrev/
Testing:
local compilation

Thanks,
  Thomas