SOLR-5525

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1547569 13f79535-47bb-0310-9956-ffa450edef68
SOLR-552: change scale function to use itself as context key instead of source

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1547571 13f79535-47bb-0310-9956-ffa450edef68