Merged revision 1578262 from trunk: LUCENE-5515: Improved TopDocs#merge to create a merged ScoreDoc array with length of at most equal to the specified size instead of length equal to at most from + size as was before.


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1578267 13f79535-47bb-0310-9956-ffa450edef68